I only use Java currently. Same program on laptop still on Eclipse 7.1 shows autocomplete.
Desktop just renewed subscription last week and upgraded from 7.5 to 8.5 and have no basic autocomplete at all. I installed over the top of 7.5.
I have exported the program from Eclipse on desktop, imported into Eclipse on laptop, so identical program, different results.
Can you clarify if “Basic Proposals” and “Other Proposal” are checked under Window > Preferences > Java > Editor > Content Assist > Advanced?
Also, can you switch to a new workspace and check if the issue persists?