The permissions are properly granted on the Samsung tablet (Android 10) and I'm able to import a file that was exported from a Pixel 4 XL (Android 11). Also, adding a custom image using "Picture Repository" works fine on the Samsung.

Export behaves slightly different on the Pixel phone than it does on the Nexus tablet (Android 7.1.1). On the Pixel you press "Continue" and then "Process" at which point the Android system dialog opens and a filename can be entered. On the Nexus you fill in the Path and Filename fields and then press "Process". On the Samsung tablet, there are no Path/Filename fields or a Continue button and nothing happens when pressing the "Process" button.

Understandably difficult to fix when you can't duplicate it. I'd be happy to help if there's anything I can do to narrow down the problem.

On a Nexus 9 tablet I'm able to export to a file, but on a Samsung tablet (SM-T500) the Path and Filename fields are not visible so export is not possible. Exporting to another IRControl Device works fine.

Also, on the Samsung tablet, when selecting "SD Card" in the "Add Picture Category" dialog and then Path, the file/folder list is empty so it's not possible to select an image. This also works fine on the Nexus 9.

It seems like these two issues could be related and that Samsung has changed something related to file paths.

I used Packet Capture and sent the HTTP POST request. The file is found but it's the wrong content type, "text/plain" when it should be "application/json". Is it possible to include the header "content-type:application/json" and if so, how?

From an app that successfully sends the command:
POST /jsonrpc HTTP/1.1
Content-Type: application/json
...

It returns:
HTTP/1.1 200 OK
...

From IR Control:
POST /jsonrpc HTTP/1.1
Content-Type: text/plain
...

It returns:
HTTP/1.1 415 Unsupported Media Type
...

Log when sending an HTTP POST request:

DEBUG fireEvent IRControl Application: Refresh-500=refresh
DEBUG fireEvent IRControlApplication: Refresh-30 tooks 7 MilliSecs
DEBUG fireEvent IRControlApplication: Refresh-30=refresh
ERROR Error while executing HTTP Command
DEBUG HTTP POST http://192.168.175.51:8080/jsonrpc {"jsonrpc":"2.0","method": "Input.Down","id":1}
ERROR Device null connected to httpgateway-01 (not accessible)
DEBUG Gateway gcitach-01 is alive
DEBUG iTach Result device,0,0 WIFI device, 1,3 IR endlistdevices
DEBUG Gateway httpgateway-01 is alive
DEBUG Send iTach Command to 192.168.175.50:4998 / getdevices

Log when sending an HTTP GET request:

DEBUG Start Event handling on Composite. Number of threads now 14
DEBUG fireEvent IRControlApplication: Refresh-30=refresh
DEBUG HTTP Result 200
DEBUG HTTP GET http://192.168.175.51:8080/jsonrpc?requ ... wn","id":1}
DEBUG Gateway gcitach-01 is alive
DEBUG iTach Result device,0,0 WIFI device,1,3 IR endlistdevices
DEBUG Gateway httpgateway-01 is alive
DEBUG Send iTach Command to 192.168.175.50:4998 / getdevices

I was successfully using IRControl to control a device with HTTP GET requests such as:

192.168.175.51:8080/jsonrpc?request={"jsonrpc":"2.0","method":"Input.Down","id":1}

After updating that device, it now requires HTTP POST requests. I've gotten the following to work from two other programs, but it fails in IRControl.

192.168.175.51:8080/jsonrpc (in the URL field)
{"jsonrpc":"2.0","method":"Input.Down","id":1} (in the Content field)

The stacktrace shows:

java.io.FileNotFoundException:
http://192.168.175.51:8080/jsonrpc
com.android.okhttp.internal.huc.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:255)
ch.cec.ircontrol.o.i.a(Unknown Source:177)
ch.cec.ircontrol.o.i.a(Unknown Source:3)
ch.cec.ircontrol.setup.activity.p$h.run(Unknown Source:150)
ch.cec.ircontrol.d0.n$c.run(Unknown Source:25)

What am I missing? I feel like maybe it needs "Content-Type:application/json" but I'm not sure how to include it.

Using your StateButton example, I created a state button to select between two audio sources. It works fine but the problem I have is that it always defaults to the "off" state. For example, if I press the button so it's in the "on" state and then change pages (such as Main) and then return to the original page, the button will be in the "off" state.

Is there a way to make the State Button retentive so the button will remain in the state it was in when returning to the page?

I'm trying to accomplish this with StoreGlobalVar and GetGlobalVar but am a little confused how to use them. Do you have an example?