This was happening before (for sure in 13.1) but getting worse in 14 beta.
TOAD is not handling the "disappearing sessions" too good.
I have profiles defined on databases that limit inactive session time - they get disconnected.
When I leave my PC with TOAD open and come back after that limit passes I need to reconnect.
If, in such situation, I hit the Session Reconnect button then all ends fine - all my sessions reconnect. However, if I try to do anything else, then TOAD usually crashes (not even showing the error dialog box) - the Windows threads are just killed immediately.
If I have several connections open (a few users in the same dtb + other databases too) then when my sessions expire and I click anything else, then TOAD hangs for 15 minutes (this might be the time on the server set for the session inactivity threshold) before communicating to me that the connection was dropped - it repeats that for every connection I had. After the last session it crashes = terminates immediately.
Usually I am only editing some PL/SQL scripts, so only editor windows are opened for my connections. Usually single edit window with several tabs that I switch between connections (e.g. run the same script on several databases).