How do I resolve RESTEASY002186 so my Wildfly 26 web application can use SSE over https? - wildfly

Question

I have a web application running on Wildfly 26 that uses SSE broadcasting and works correctly with http. However, when I switch to using an https endpoint, I get Wildfly log entries of:
WARN [org.jboss.resteasy.resteasy_jaxrs.i18n] (default task-1)
RESTEASY002186: Failed to set servlet request into asynchronous mode,
server sent events may not work
This happens with each registration attempt of the https endpoint but I never see this when registering with the http endpoint.
Testing with curl against the http endpoint results in curl waiting for events to show up (and keeps printing them out as it receives them) until I quit. Using curl to test the https endpoint, I will see the same headers I got from the http endpoint, namely:
HTTP/1.1 200 OK
Connection: keep-alive
Transfer-Encoding: chunked
Content-Type: text/event-stream
But after printing out my registration successful event, curl seems to believe the stream is closed and exits -- giving me my command prompt back.
My #GET MediaType.SERVER_SENT_EVENTS registration endpoint will create an OutboundSseEvent and send it to the SseEventSink to acknowledge successful registration to my SseBroadcaster instance (this is the event curl sees and prints before exiting). I then log a registration successful message before exiting the method. All of this appears to work correctly for both http and https but the stream doesn't stay open once the request endpoint completes because of the failure to run asynchronously as outlined above.
I have not found information on the causes and/or workaround solutions for my RESTEASY002186 problem. I posted a question on this issue last week using the Wildfly Google Group (https://groups.google.com/g/wildfly/c/SO2eHdvMEko) but thought I would try a wider audience since this doesn't seem to be a commonly experienced condition. I don't see any indications during initialization that WildFly will be unable to use asynchronous mode, it just complains when it tries and fails... Any help would be greatly appreciated!
Edit 6/6/2022
The code is running on an isolated network so I can't just cut/paste the code here, but I gutted the resources file to a bare minimum -- just leaving enough for the client to be able to register. The problem remains unchanged. The code is now essentially:
#Path("sse")
public class SseResources {
#GET
#Produces(MediaType.SERVER_SENT_EVENTS)
public void listen(#Context Sse sse, #Context SseEventSink sseEventSink) {
SseRegComplete regComplete = new SseRegComplete("sse-server");
OutboundSseEvent event = sse.newEventBuilder().
name(regComplete.getType().toString()).
id(regComplete.getEventId()).
mediaType(MediaType.APPLICATION_JSON_TYPE).
data(SseRegComplete.class, regComplete).
comment("Event Stream Registration Completed Successfully").
build();
sseEventSink.send(event);
}
}
Before the above simplified code, I had declared the resource as #ApplicationScoped, had Sse injected into it, and kept a reference to the SseBroadcaster so I could use it whenever an event would come in. I was catching the events to broadcast by using an #Observes method (which I also got rid of). I was calling register(sseEventSink) on the SseBroadcaster in the listen method so I could later call broadcast(outboundEvent) whenever I had updates to publish. I got rid of all that just to see if I could get the stream to stay open but to no avail. I still get the RESTEASY002186 message and curl still exits after printing out the regComplete event sent to it in the code above.
Edit 6/7/2022
Yesterday I was able to get my code working in a new vanilla Wildfly 26 install using an https endpoint URL by following these configuration instructions. Something I hadn't mentioned in the original post is that I am trying to add SSE functionality to an already existing app. It is several years old and we actually moved to Wildfly 26 about 6 months ago because of the log4j vulnerability in the earlier version of Wildfly we were using. I suspect that the problem is related to either our Wildfly configuration (perhaps because old settings were brought over that shouldn't have been) or some 3rd party dependency that is preventing Wildfly from using asynchronous mode.
We are using Shiro for authentication and authorization against an LDAP server -- perhaps Shiro has some hooks into the Wildfly runtime that are causing issues? After initial login, we use a session cookie in all subsequent calls. That is a difference from my test server but I don't think it is relevant because the call definitely passed authentication before executing the registration code. The only other thing that comes to mind right now is our web app ships with LogBack and tells Wildfly not to use the default logging framework.
I plan to start today by comparing the two standalone.xml files to see if anything jumps out at me as being fundamentally different. Is there anything else I should be checking for differences (I think there is a domain.xml file somewhere...)?
Edit 6/14/2022
This definitely has something to do with Shiro being in the loop. When I edit the web.xml file to have Shiro's filter-mapping url-pattern to not include the SSE endpoint, everything works as expected.