The guess feat button works just fine for recordings and releases when using it on a title such as Y (feat. X). For release groups, an error results:

Uncaught TypeError: undefined is not iterable (cannot read property Symbol(Symbol.iterator))
at b (relationships.js:19)
at O (guessFeat.js:140)
at T (guessFeat.js:164)
at guessFeat.js:56
at Array.flatMap (<anonymous>)
at guessFeat.js:56
at E (guessFeat.js:120)
at guessFeat.js:77
at Array.reduce (<anonymous>)
at guessFeat.js:66
at E (guessFeat.js:114)
at S (guessFeat.js:213)
at HTMLButtonElement.<anonymous> (guessFeat.js:272)
at HTMLDocument.dispatch (jquery.js:4665)
at HTMLDocument.v.handle (jquery.js:4333)
at HTMLDocument.r (helpers.js:71)