Well, that's the thing, we can't possibly guess. Over the years I've seen lack of hard drive space being responsible for all kinds of weird and unpredictable stuff. It might help the immediate problem, or it might not; but I guarantee you this - it will definitely prevent other problems in the future.
And make sure you run CleanMyMac.
This is nasty. Brian always says you should have one third free hard drive space, and you don't even have one tenth. Barely even one twentieth.
You HAVE to clear some space. NOW.
Ok, wow. Something is screwy.
If you are in Photoshop, and go to File>Open, can you navigate to the jpeg file you just tried, and open it that way?
Also, can you do this for me? https://www.damiensymonds.net/thread1.html
One more question, then I'm completely stumped ...
I know that Photoshop, in its Preferences, has a button that says "Reset all warning dialogs". I assume Lightroom has the same button in its preferences. Can you find it?
Ok, now check Lightroom's preferences to make sure they're pointing to the right version of Photoshop, I guess.
30 days, Jenny. Just give me 30 days to change your life.
https://www.damiensymonds.net/bridge-30-day-challenge
Not only will your life be MUCH simpler, your images will be better as well.
Ok, we'll come back to the colour profile problem. Let's fix this problem first. Does it give you an error message when you try to open a photo from LR to PS?
That's correct. Yet another reason why the "Macs are best for photographers" belief is a big fat fallacy. Macs are the WORST.
So, do you have another screen in your house that you can plug in to the computer and run as a second screen, and see what happens when you calibrate that?
If you could elaborate on that, it would be great.