Random Vertex Disconnect Over Entire Model...... (Maya 2019)

Amank679

Hi All,

I've come across an issue I feel i've invested way too much time trying to fix. I'm working on a model which will mostly be continously modelled for which I did some  mesh combine and target welding. For whatever reason, when I go to UV Map it, it says certain edges and verties havent fully joined wit the model. I feel like i'm constantly target welding areas that I've already done before. Not sure what's going on.

If it helps, I'm using Maya 2019

Please let me know your thoughts.

I've attached images below.

Thanks in advance!