Hello Thomas,
I'm sorry to hear that you are experiencing these issues. Thankfully you have taken the appropriate steps to properly troubleshoot the SD Card in question.
Sadly though, it seems that the issue is with the SD card itself. And because of the nature of the solid state memory that SD cards use, there may be no way to save it. It's acting as if it is corrupted. An SD card can become corrupted by extreme temperatures, magnets, physical damage, etc...
You may not have put it in those conditions before it started acting funny, but have you ever had it in those conditions? If so, that could be the reason behind it's corruption. Memory devices sometimes fail immediately, but most of the time, they slowly degrade. Is it an older SD card? That could be a reason as well.
Needless to say though, I do believe that the SD card is done for at this point. Best thing to do is maybe leave it out on a table in a good, safe area. Wait until tomorrow and try it again on all of those devices just to get your data off of it. Then, get a new one.