Multi-Columns not always working correctly

[baszero]

In my PDFs I switch from a regular Full-Width Layout (1 column) to a temporary 3-col-layout, in order to insert 3x3 images, like here:

However, sometimes the images get mis-aligned. What could be the cause? Any ideas? THANKS FOR YOUR HELP.

in both cases the images have the same size and same format.

[baszero]

found the root cause. software bug, not a library issue. --> CLOSED