Shift click appears to be buggy. Numerous people such as viper daut and myself occasionally see it doing strange things such as "skipping" an action or not doing that action. However, it could be that it's just misclicks there too. I have never seen or experienced any issue with shift and delete though like you had.I was sure this gonna be the fisrt answer but I always check minimap for not over delete walls and im pretty sure tc was not in white color like the wall, and I didnt see in middle box either where units appeared. Maybe it was my failure but im not convinced about that
I only reacted with a since this has happened to me on more than one occasion... Far too many tbh. For myself I'm pretty sure it was a matter of having my tc selected when starting to shift-click my walls. Has led to some "interesting" matchesSometimes happen to me that im going to delete the wall at the back selecting all with double click then with shift pressed i select the gate press shift + supr to delete all and voilá tc is gone... That's happen to me 2 times someone else?