When plotting multiple images with masks in Firefly, only the most recent mask will be plotted for all the images. When viewing multiple images being plotted, you can see how the masks of every image get updated to the last one. Occasionally, it appears that all masks are correct until zooming in or changing the view of the older images.

An example of this can be seen in https://github.com/lsst-dm/ap_pipe-notebooks/blob/873176ea1d87870c1678037b13e7ff48bd4c56fb/notebooks/Firefly-Bug-Notebook.ipynb