Pen Tool issues

The pen tool has a load of issues I've never seen before, has been happening over the last 2-3 weeks. I have not changed any settings. Problems:

1. When creating a new path, I place the first node down. When clicking for a second, a path is not drawn between them (just nodes shown). I have found a temporarly work around where I select 'Shape', draw a couple nodes, then switch back to 'Path' where the conecting path shows again. 
2. On occasion, when aiming to place the node and then drag it to create a curve, the node doesn't show a handle but just sticks to my on screen pointer. No handles are shown. 
3. The worst case of this creates an undesirable flickering (brightness changes) of the image and the pen tool behaves like example 2. 

These issues happen with a degree of randomness, sometimes after loading a second or third large image (12,000x800px) into a session (the previous images not even open any more), but occasionally on the initial opened image with a new session of PS. Sometimes a PS restart will fix it, sometimes I have to restart the computer. It's very frustrating for such a previously reliable tool.

I am running a 2019 MBP - 2.4GHz 8-core i9, 32GB, with the AMD 5500 8GB card. I always do the latest CC updates.