No, this is not a bug. It is a limitation on the number of image textures that can be displayed with Eevee. 

If this happens, you can either hide some layers as you work on additional layers, or use the merge visible button to merge all visible layers to a single layer.

I will send emails after every update (major, minor or build/patch) to anyone who has consented to receive emails through Blender Market. Or, even better, you could join the PBR Painter Discord Server, in which I'll announce every new update in the announcements channel.

Yes! I welcome and very much appreciate any feedback and/or suggestions you may have. 

It is my goal to very actively manage this addon, which means constantly updating it according to the feedback I get. 

You're encouraged to join the PBR Painter Discord Server, which has a specific channel for feature requests.

You can also contact me using Blender Market's messaging system or email directly at support@pbrpainter.com or over twitter (@PBRPainter).

You're encouraged to join the PBR Painter Discord Server, which has a specific channel for help with the addon.

Alternatively, you can contact me with any questions you may have, either using Blender Market's messaging system or via email at support@pbrpainter.com, or over twitter (@PBRPainter). 

You're encouraged to join the PBR Painter Discord Server, which has a specific channel for bug reports. 

Alternatively, you can report any bugs either through Blender Market's messaging system or email directly at support@pbrpainter.com.

I will endeavour to include any bug fixes with the following version update.