Guys, I'm sorry, you were right. After diving deep into my 5 year old code and tidying it up a bit, the whole thing works with MaxSDK34.
Maybe you know the feeling of analysing your old code over and over again and wondering why the hell you made it so complicated back then. So you rewrite the code and it works.
No problems with agraham's MANAGE_EXTERNAL_STORAGE, no problem accessing the download folder.
Lost in the code. The explanation is then actually quite simple.
The permission itself always worked. Since this permission was stored in the app once, it was enabled on the phone for this app. I need it to access a file created by another software in the download folder. Its data must be processed. The name of this file is variable. I determine it with the wildcards2 routine. The name of the file then ends up in a variable. If you then delete this variable, of course, there is no longer a file for the app in the download folder. I have no idea why this suddenly worked with SDK32. I must have changed something else in the code.
Evolutionary programme code can become very difficult to control over the course of time, especially as, thanks to Google, you are constantly forced to modify functioning code again and again and thus introduce new errors.
The error was where it always was. It usually sits right in front of the computer...
It is far from over. The GPS library is ‘outdated’ and must be replaced by the GNSS library. Definitely not a problem. I suspect nasty surprises...
Many thanks for your help and persistence, in the end you were right. Case closed for now...
Cheers