Gallery lightbox not working after J4 to J5 migration - images have height: 0px

[tymekkoki]

Hi,
After migrating from Joomla 4 to Joomla 5, I'm experiencing issues with Phoca Gallery lightbox.
Problem:

• Images open in lightbox but display as black screen

• Images have height: 0px in inline styles

• data-size attribute shows incorrect dimensions like "800x0" instead of "800x600"

Setup:

• Phoca Gallery: 6.0.1

• Phoca Gallery Plugin: 6.0.0

• Joomla: 5.x

• Detail Window: Bootstrap Modal Popup Window (also tested PhotoSwipe, Magnific, Moving Images - none work)

What works:

• Old galleries created before migration work fine

• New galleries created after migration have this issue

• Manual thumbnail recreation fixes the problem - recreating thumbnails for affected images corrects the data-size attribute

It seems like the initial thumbnail creation process is not detecting image height correctly, but manual recreation calculates dimensions properly.

Any ideas what could cause this? Is there a setting I'm missing or a known bug with J5 migration?