Two active data folders created and used concurrently, but only one accepts new data

App version: 2.0.3
Android version: 4.1.2
Device model:GT-S6810P

Expected behaviour: Up until September 2020 my data folder was an external SD card and I have got about 8GB of podcasts still in that directory.

Current behaviour: I had a warning that I was running out of storage space in October 2020 and upon checking found that I still had approx 6GB of my 16GB external SD card available. However the AntennaPod Data Folder had changed to the internal storage (/storage/sdcard0/podcasts) which was indeed virtually full.

I have continued to use AntennaPod daily since that time and all new podcasts go into the sdcard0 location, but all pre-Sept-2020 podcasts are still listed, indexed and playable in the old external SD card location and play and delete exactly as they should.

If I try to change the data directory then my only option is the sdcard0.

Another application that uses the external SD card can still select and access the card and the external card is normally accessed in every way from file manager, thus suggesting that the problem is with AntennaPod rather than Android.

Environment: As it took me a number of weeks to realise that there was a problem I can’t guarantee that nothing changed, but this old phone is only used for AntennaPod and (very rarely) as a SatNav. No mail, calendar, games, not even used as a phone.

First issue - How to write to external SD card again and then
Second issue - How to merge SD0 data back with the external SD card.