No ring group ring tone after transferring from IVR (solution?)

[SteveITS]

Similar to @RossFS in https://www.3cx.com/community/threads/no-ring-group-ring-tone-after-transferring-from-ivr.65023/ I wasn't getting hold music when the IVR transferred to a ring group. Unlike that post, our brand new installation doesn't have a silent.wav file. It does have an empty.wav file, if I click the down arrow in the Music On Hold Settings, but that page did already show onhold.wav in the Music file 0 slot. I clicked OK on that page, and after that music does play after transfer to IVR. Note before that hold music did play at other times. Just posting in case someone else runs across this.

Linux v16.0.273, installed a week ago.