Comment 5 for bug 1767314

Further investigation with a recompiled version more recent than that shipped with 18.04 yields that syntax highlighting failure is caused by redrawtime being exceeded - often triggered after using G to move to the end of the file. It is not possible to set "syntax on" manually at that point as it immediatetly gets disabled again unless you move to the start of the file with g.

This explains the "persistence" due to the "jump to the previously edited line in the file" setting being set - but forgetting it upon deletion of .viminfo as this is where this Info is stored. Without it vi opens with the cursor at line 1.

In my case this problem has occurred following an upgrade and has never happened before on the same hardware running the same applications for many years with lots of files being edited multiple times every day - day in day out. Ie something in the timing dynamics when running vi has changed wirh 18.04

See https://github.com/vim/vim/issues/2790 for further discussion and possible workarounds.