Issues when sending media to a meeting

I'm facing some issues while sending content into the meeting. I'm getting the error The supported buffer sizes for the format Pcm44KStereo are: 10ms 20ms when I try to send audio in that format, no matter how I adjust the size of the buffers. For example I get the error when the buffer size is 3528 bytes long which, divided by 4 (sample length, as the bit depth is 32 bit) and divided by 2 (as it is stereo) gives 441 samples which is 10 ms long. Same happens when the buffers are 7056 bytes (equals 882 samples = 20 ms).

For generating the buffers, I'm using a GStreamer test source and configuring the audio in PCM, 44100 Hz, signed 32-bit little endian, stereo, am I correct here? If I switch to mono I don't get the error, but I hear distorted audio in the meeting. If I configure the audio format in Pcm16K and my source as PCM, 16000 Hz, signed 16-bit little endian, mono, I can send audio to the meeting without issues, but I was using Pcm44KStereo for extracting audio already, so this is a setback as I cannot configure different formats for send and receive.

When sending video, I was only able to do it using the NV12 format. When trying to inject H264 I get a Microsoft.Skype.Bots.Media.SkypeMediaException with the message Deliver video source media buffer and I cannot find documentation about this. I was expecting to inject H264 content, so this makes me add a decoding step. Am I missing something in order to inject H264 content?

Update: I'm being able to inject audio (Pcm16K) and video (NV12), but I'm occasionally getting a Microsoft.Rtc.Internal.Media.MediaApi.MediaApiInvalidOperationException with message Deliver Audio source media buffer, similar to the error mentioned above. It sometimes arises right away, it sometimes arises after 3 or 4 minutes of sending the media into the meeting. I can't find where it's coming from, what could this be related to?

Start with the GStreamer test source configuration and the Deliver Audio source media buffer and Deliver video source media buffer errors described in the issue. Compare the Pcm44KStereo, Pcm16K, NV12, and H264 inputs against the documented media-source requirements; done means identifying the supported formats and a reproducible cause for the failures.