...what can I do to work around this problem?
Use Media Encoder to flip the audio file from 44.1 to 48kHz and try that.
Yeah, that worked. Any way not to do that? Thanks
I use CD audio (44.1K) all the time with my video clips (48k) and never have an issue. It's not normal for you to require changing the sampling rate for it to work. If it's just that one music file, it may be a glitch, but if it happens with all music files, something is wrong.
As Jim points out, there should be no problem mixing 44.1 and 48kHz
audio together in the same timeline... I do it all the time.
I suspect there is an anomaly in your original 44.1 audio file
that re-encoding to 48kHz solved (as a workaround).
I'm willing to bet that if you flipped the original 44.1 audio file
to a new 44.1 file it would work without error as well.