What I’m going to do, now that the creative dust has settled a little, is see if I can replicate this error. If I’m able to, I’ll post steps to repro so others can try it and maybe something can be chased down and isolated as a cause.
If I’m unable to replicate the error, I’ll report that as well, since negative findings can also be useful.
This may be related to files vanishing from within binders after moving a project from DB to an iCloud-synced folder, depending on what is happening on the back end with sync in general. This is only an inference based on the fact that the topic I’ve posted at the link above, and this topic, both began manifesting in early October. Two weirdnesses affecting related systems smacks of an introduced bug, though whether it’s Dropbox’s or Apple’s, I’m not sure.
@AmberV noted, upthread and in passing, that DB has been forced to adopt some of Apple’s sync tech, which is becoming more poorly documented for developers, and I’mm’a bet an entire cupcake that this is at the root of it. There is file f*ckery afoot in the Hallowed Halls of Jobs, and we’re seeing esoteric and abstruse collateral effects.