When I preview my app, tells me to check my blocks, although I have none, and even when I downloaded the app, it still didn’t work. It stopped working very suddenly. I used the drag and drop builder.
BTW I have an android
I could try to help you if you could send a screenshot a link to the project. Maybe there are some components wich android doesn’t support. Here is the list of unsupported components in Preview
I figured it out. It was the banner ad, and I didn’t have premium. Even though I removed it.