I was having the problem some time ago. It started when I have to do remote work.
I was able to access share on my PC before remote work, but after I start to do remote work I suddenly found I cannot.
The cause for the problem was my business anti-virus solution. My business in Ukraine uses a business endpoint security program (it may not be so well known where you are but it's popular in business here). After work from home I had to install on my home PC. My work IT was able to change policy to resolve the issue I and my coworkers had on our home PCs.
So please make sure check your anti-virus, even if you use a different one because sometimes they can restrict network access too much.