Hi @Anonymous ,
How do you collect the images into a Collection within your app? Using Camera control to capture pictures?
Could you please share more details about the formula you used to capture the images captured via Camera control?
Based on the needs that you mentioned, I have made a test on my side, and don't have the issue that you mentioned. The App's configuration as below:

Set the OnSelect property of the Camera control to following:
Collect(CapturedImages, Camera1.Photo)
Set the Items property of the Gallery to following:
CapturedImages
In addition, I also made a test on my side, if you type above Collect formula within the OnSelect property of another Button control rather than within the OnSelect property of the Camera control itself, the CapturedImages collection would contains empty record.
So please do not type your Collect formula within the OnSelect property of another button control, instead, you should type it within the OnSelect property of the Camera control itself.
Please consider take a try with above solution, then check if the issue is solved.
Best regards,