IDE locked in Generic 8266 mode

I am using Version 2.0.0-beta.10 on Windows 10 and was originally programming Pro Minis successfully. Recently I developed software for ESP-01 using the Generic ESP8266 Module, again successfully.
However I am now wanting to program more Arduino Pro Mini's but find that any previous Pro Mini sketch I load gets the board setup changed to ESP8266.
When I look to change the board setting back all the Arduino settings are now greyed-out. How do I resolve this issue please?

You are 2 versions of the beta behind. My first move would be to update to version 12 of the beta or you could, of course, use the original IDE instead

There is even a newer 2.0.0-rc1 release available, which has some pretty significant advancements even beyond 2.0.0-beta.12.

It hasn't been published to the arduino.cc software page yet, but 2.0.0-rc1 can be downloaded from the release page here:

The downloads are under the "Assets" section of that page.

I have upgraded to 2.0.0-rc1 (it took over an hour) and can now select Arduino Pro or Pro Mini - great! However this version says "Debugging is not supported by Arduino Pro or Pro Mini" when I compile and I cannot upload the code to my device interface on the USB COM port? One step forward, two steps back.

Where does it say that? It is normal and expected for it to be shown in the tooltip and to the right of the board selector when the mouse pointer is over the "Debug" button:

image

The IDE has an advanced integrated hardware debugger and this is only compatible with specific boards. The Pro Mini is not one of those boards.

Please provide a detailed description of the problem you are having while uploading.

If you are getting any error or warning messages, post the full and exact text of the error messages in a reply here.

I had a sketch loaded and it compiled successfully with normal output. There was a recognised interface and port selected. When I clicked the download button nothing happened at all. There was no text output.
I have tried to reload the IDE but now it does not find my arduino directory with my scripts!

Please read the information here to learn about that bug and the workaround for it:

Please provide more details about the problem you are having with the IDE finding your "arduino directory".

If you are getting any error or warning messages, post the full and exact text of the error messages in a reply here.

That "unable to find Arduino directory" seems to be a one-off, I cannot replicate it now (I am running Norton anti-virus). Should have screenshotted it but the error message only flashed up briefly.
Turning on verbose output, compilation ok but sketch/upload causes Indexing to take place (albeit slowly). After the indexing finishes nothing more occurs.

Please read the information here to learn about that bug and the workaround for it:

https://forum.arduino.cc/t/upload-does-nothing/930864/27

Also I have noticed another curiosity. If I select File/Open New Window, the new window opens with the same port connected. Successive windows have the same port selected but try to reconnect as one would expect the second window to do also.

Thank you, the workaround enables me to program the Pro Mini.

You are welcome. I'm very glad to hear it is working now. Hopefully there will be a true fix for the upload bug soon.