Permanent Quartus Prime internal errors during Analysis and Synthesis of Compilation Flow on two purchased Quartus versions 18.1.2 and 19.3.

The complete uninstall and new re-install have been tried to no avail. The computer details: OptiPlex 7070, i7-9700, 48GB RAM, Windows 10 Pro x 64bit. Both Quartus versions compilations worked well...