Indexing slow or simply no longer working until restart

Question

Using Intellij Ultimate version 2020.3.

A support colleague in the name of fixing my laptop, went to delete some Intellij related data from my KeyChain on my MacBook Pro.

Ever since then, no longer able to get instant results for my changes. Couple of examples.

I could add a @Test and write a method. The @Test will not change to yellow color (Using Dracula Theme) until I restart the IDE again.
I could have a logic like follow.

IDE would complain null pointer for following. Good.

String value = null;
String new = value.replace("a", "b");

Now I go and change the logic to following.

String value = "a";
String new = value.replace("a", "b");

The IDE will still be stuck on complaining that this would produce null pointer. Until I restart IDE and error goes away.

Could I please get some help on how I could fix this please. It is extremely bad interface experience.