@girish, thanks for following up. I tried a handful of things:
Stop & start of the Lychee app.
Full Reboot of the Cloudron Server.
Uninstall and reinstall of the Lychee app.
Increased allocated memory.
I believe it was due to the allocated memory. I increased it from 256MB to 1GB this morning and everything is working fine. I can do some further testing when I have time to see if I can reproduce it. Either way, I'm now able to upload a photo (or multiple photos simultaneously). It would error uploading a single 5MB photo before this change.
@girish Same in Nextcloud. In Nextcloud ImageMagick is used to render the preview for the images. At the moment this does not work with the Cloudron Nextcloud pp. But your solution should solve this too 🙂
@T3Gunner Ah, I suspected as much. This is not a support forum for Lychee - it's for the Lychee package of Cloudron.
I wish I could help you out anyway but that seems unlikely because the question you asked is very much dependent on how the app is installed by the control panel. So you have to ask your question either in the Lychee project on GitHub or cPanel forums.
Thanks for your help @girish, I'll just create a gallery using PIWIGO