the-rebel-agent:
I know, but worth the try. Last night I tried my new Sandisk. Same weird behavior. I took the wavs from Windows OS, small ones, and ad4 files only were 2kb long. Converted 16 tracks, some of them played great, other same defect. Only for a few seconds. It is not about the size, there is something wrong with the micro sd card brand, model or the audio module is defective. I requested a new one from eBay vendor.
i had same beahaviour, i solved first encoding the wave into 32khz then converting to AD4