Hi Jones,
Glad to read that you’ve fixed the PHP issue
UploadRecordings trials will compress in a single zip archive all the recordings made at the time the trial is executed, which haven’t been uploaded yet. If you have a single MediaRecorder element in each trial and you insert an UploadRecordings trial after each recording trial, and assuming each UploadRecordings successfully uploads its zip archive in time before the next recording has completed, then each uploaded zip file will indeed contain a single recording. However, there are plenty of situations where zip files will contain more than one recording, as you can imagine. This is why you cannot name zip files based on single elements (or even single trials) and PennController simply randomly generates a unique filename
I understand it might not make for the most straightforward data processing, but the results file lists all the filenames of the archives that were uploaded for a given submission (look for the UploadRecordings lines), so you can unzip the content of those files in a dedicated subfolder (which you can name after whatever participant-identifying string you use) and look for the recording files named after the MediaRecorder elements in those subfolders
Jeremy