it is stored in /Documents/Infiltrometer/data.csv. When I use the AI companion, I can see the file I saved in that directory using USB - PC. That file is not created when using .apk.
It would really help if you provided a screenshot of your relevant blocks, so we can see what you are trying to do, and where the problem may be.
To get an image of your blocks, right click in the Blocks Editor and select "Download Blocks as Image". You might want to use an image editor to crop etc. if required. Then post it here in the community.
Taifun
PS: please remember to NOT upload your project (aia file) into the community, as it contains a paid extension
If you tested with Companion beforehand, you cannot access / overwrite this file with the APK because it was created by another app (Companion). So you must delete this file beforehand with Companion or change the filename with the APK.