antlr4: actions 'causing' left-recursion errors - parsing

Question

The grammar below is failing to generate a parser with this error:
error(119): Sable.g4::: The following sets of rules are mutually left-recursive [expression]
1 error(s)
The error disappears when I comment out the embedded actions, but comes back when I make them effective.
Why are the actions bringing about such left-recursion that antlr4 cannot handle it?
grammar Sable;
options {}
#header {
package org.sable.parser;
import org.sable.parser.internal.*;
}
sourceFile : statement* EOF;
statement : expressionStatement (SEMICOLON | NEWLINE);
expressionStatement : expression;
expression:
{System.out.println("w");} expression '+' expression {System.out.println("tf?");}
| IDENTIFIER
;
SEMICOLON : ';';
RPARENTH : '(';
LPARENTH : ')';
NEWLINE:
('\u000D' '\u000A')
| '\u000A'
;
WS : WhiteSpaceNotNewline -> channel(HIDDEN);
IDENTIFIER:
(IdentifierHead IdentifierCharacter*)
| ('`'(IdentifierHead IdentifierCharacter*)'`')
;
fragment DecimalDigit :'0'..'9';
fragment IdentifierHead:
'a'..'z'
| 'A'..'Z'
;
fragment IdentifierCharacter:
DecimalDigit
| IdentifierHead
;
// Non-newline whitespaces are defined apart because they carry meaning in
// certain contexts, e.g. within space-aware operators.
fragment WhiteSpaceNotNewline : [\u0020\u000C\u0009u000B\u000C];
UPDATE: the following workaround kind of solves this specific situation, but not the case when init/after-like actions are needed on a lesser scope - per choice, not per rule.
expression
#init {
enable(Token.HIDDEN_CHANNEL);
}
#after {
disable(Token.HIDDEN_CHANNEL);
}:
expression '+' expression
| IDENTIFIER
;