I’m not sure if social anxiety is the main issue, as the problem is reproducible in the solitude of my study – as soon as I actually try to play along with a song that’s relatively new to me.
But it’s getting better already. It’s almost as if the awareness helps me deal with it.
Another thing that also helped is that I now have iReal Pro to work, plus I got a playlist with all their (I should probably say our) songs. I find that practicing over those is easier, for reasons that I cannot fathom.
Yesterday was the first band rehearsal with all musicians present. The one song I had worked on went better than I had expected.
I think socially challenged is a good name for it. It doesn’t really cover that people make me really nervous and the uncomfortable feeling i have when I’m out of my room.
Being frightened of other people isn’t great. I’m ok, though. I got me a nice bass and some free time.
I think @autumnsdad1990 has the right perspective but we are all different and have different fears.
Having said that, I believe that there is a big difference in playing in jam sessions with like minded people, as opposed to actually being part of a band.
In jam sessions everyone is there just to learn and enjoy themselves for an hour or two.
In a band setting you are there to get everybody together on the same page ready to perform a set for an audience and are typically being paid to perform. You enter the world of deadlines, stress, and egos to name but a few things. After a while it stopped being fun for me anymore.
I gave up the band setting many years ago, for these reasons, but still go to several jam sessions a week, or did pre Covid, and will again when this crap is over, or at least slows down a lot.
In the jam sessions I attend, lead sheets are sent to individuals that want them to practice at least a few days ahead of time. It is up to the individuals to practice, or not. Typically a new arrival will not practice and then wonder why they are struggling. Usually the next week they have practiced and are having more fun and a better time.
Really for us in jam sessions that is what it is all about
ie. JUST HAVING FUN AND BEING WITH LIKE MINDED PEOPLE 
I suggest just going to a jam session and seeing what it is all about because playing with and learning from others can really help you to get better. Don’t even bring an instrument, although I’ll bet that if you don’t you will regret it 
OK, intermediate status report!
First of all, while I was initially worried about being frightened of people (I’m not – usually people are frightened of me, and I can see why…), or that I have performance anxiety playing with others – a little experiment showed that it was triggered by other people (other than a drummer, with whom I latch on immediately) playing their part of the same song at the same time, which sent me into a stack overflow-type situation – too many external stimuli to process while playing myself. It also happened when I was trying to play along with a Youtube clip. Playing the bass part “dry” was no problem, but as soon as I was trying to play along with the Youtube clip, my brain froze.
ENTER IREAL PRO AS A PRACTICE BUDDY
I have gotten IReal Pro to work on my PC, and I’ve got the songs in an IReal playlist, which is what I am practicing with right now. I am still a long shot away from being able to sight-read and play at the same time, so I really need to practice these songs. But IReal Pro’s playing is … kinda bland, to the point where it’s easier for me to practice along with than a Youtube video. Which is ideal for me; it doesn’t feel like I’m overloaded, and I can work on the songs until I feel that I really have them down.
This… feels promising. I’m counting on it that having the songs in my head will help me to feel more relaxed when I get to play them in a band setting.
Next band rehearsal is Monday 18, so that’s when I get to find out if this approach works.
Great news, Pete. Work it like a Sherpa, dude. You’ll get to the summit in no time.