We are getting it but it seems to be triggered by some unknown factor. Just having two TW files open doesn't automatically do it. Seems like it is triggered by something and the only way to get it back is to close down the instance having the problem and relaunch ArchiCAD and all seems to be fine again.... until the mystery trigger happens again.
kevin s burns, AIA
massachusetts, usa
AC25 (1413), since AC6
Windows 10
Intel Core i7 -8700 @ 3.2 GHz~ 16 GB ram