This is strange.
Either the progress bar is only 1/5th (the real file size is ok, but not the progress bar), or the file size is not complete (in which case the progress bar is correct). Which is it? What is the end file size.
There could also be an error in the memory identification (does it still say 4MB on the flashinfo line)?
As I understand your message, downloading stops (it does not "hang").
You can activate 'Debug GPS' /'Debug GPS Connection' in the menu. The latter creates a gpsRawDebug.txt file that logs all serial transactions which can enable me to identify the issue.
I tried a full download in V2.1.4 where I was able to get the 4MB of memory.
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