New M5Stack user here..I encountered the same problem with a CoreS3 and getting the same "invalid timer number" error messages when trying to configure the IR Unit. The S3 was reflashed to UIFlow 2.3.3, but this did not resolve the problem.
yuyun2000's helpful suggestion didn't work either as timer_id does not appear to be in the constructor for the IRUnit. Is this a more fundamental software problem?
The IR Unit with UIFlow2 is completely unusable at the moment