I did reinstall Enscape using the version 3.3 installer, without deactivating my license, and it worked with no issues, so I'm up and running again. I have also sent a feedback report with logs.
Thanks very much for you help. I hope the issues with version 3.4 can be resolved without my having to do something major, like a new graphics card. My workstation has 30 GB of ram and an NVIDIA GeForce GTX 1660 Ti. This gives me 6144 MB of dedicated video memory and 22,500 MB of total available graphics memory.