Terminal rule ID not matching valid values for ID - eclipse

Question

I'm trying to define a rule where one element is the perfect candidate for the common terminal rule ID. When I launch the editor to test with sample code, the ID rule is not matched for the string "ABC":
Define : ABC : Holder_1
I get "mismatched input 'ABC' expecting RULE_ID".
Is there something in my grammar conflicting with the ID rule to cause this error?
This is my grammar file:
grammar com.testco.Test with org.eclipse.xtext.common.Terminals
import "http://www.eclipse.org/emf/2002/Ecore" as ecore
generate defwiz "http://www.testco.com/Test"
Define_Holder:
'Definition' ':' holder_name=ID ':' holder_number=HOLDER_NUMBER (':' attribute=define_attr)? (':' pad=holder_pad)?
;
holder_pad:
HEX
;
Type:
TYPE_TERM ':' type_value=TYPE_VAL
;
//***************** TERMINALS *****************
terminal TYPE_TERM:
'Type_' INT+
;
terminal PROFILE:
(PROFILE_ID)(PROFILE_ID)'.'(PROFILE_ID)(PROFILE_ID)
;
terminal HOLDER_NUMBER returns ecore:: EString:
'Holder_' INT+;
terminal HEX returns ecore:: EString :
('0'..'9'|'A'..'F')
;
terminal PROFILE_ID : '^'?('a'..'z'|'A'..'Z') ('a'..'z'|'A'..'Z'|'0'..'9')*;
//***************** ENUMS *****************
enum define_attr:
BINARY='Binary' |
SCRAMBLE='Scramble' |
FORCESIZE='ForceSize' |
FIXEDSIZE='FixedSize'
;

Answer 1

Your rule PROFILE_ID shadows the ID rule for almost every case (except for the underscore).

Answer 2

Yes, it's likely that lexer scans ABC as HEX terminal. Try to define the latter, for example, as follows:
terminal HEX returns ecore:: EString :
'0x' ('0'..'9'|'A'..'F')
;