When using a construction like this:
<b-btn v-b-toggle="collapseId">...</b-btn>
<b-collapse visible :id="collapseId">...</b-collapse>
plus some additional circumstances which are unfortunately yet unknown to me, the Button will, a few milliseonds after being initially displayed correctly, get the class collapsed added, and thus be displayed incorrectly (as if no visible tag had been added to the b-collapse).

This happens with release 2.0.0.rc16. It does not happen with 2.0.0.rc15. I believe the problem to have been introduced with commit 6f899fc , where a comment states
// state is initially collapsed until we receive a state event
which is not the case due to visible.

• Operating system and version: Windows 10
• Browser and version: Chrome 73.0.3683.86
• BootstrapVue 2.0.0.rc16

I have not been able to reproduce this with a minimal setup. We observe this problem on a large page with several collapse instances. All instances are affected, and it is 100% reproducible on that large page.