It could be related to a performance issue. Running windows 10 on an I5 with 16GB RAM. But the same problem arises even on the smallest project and I never have performance problems of ANY sort in 10.
Performance meter shows very little activity
When I restart my PC I can still maintain and enter inserts in 10.5. After a while suddenly the attached screen appears prohibiting any maintenance of or adding inserts. If I close 10.5 and open the same project in 10 there is no problem, nor have I ever had a similar problem in 10.
If I restart my PC for a while again I can maintain inserts then it re-occurs.
10.5 utterly useless as of this time.