Scott, thank you very much for trying to reproduce and for the contextual information. Is there a timeline on the new architecture? Sounds like it should prevent issues like this entirely.
On reproducing the issue: just to clarify, I am using the standard current web client (not "classic" and not "beta") on Firefox 66 with no add-ons, and the mac client version 7.9. I am still able to reproduce. When you say the "old client" are you referring to the current stable web client, or classic? Should we be using the beta instead? Thanks again.