More Dropshadow / Group Problems

I just posted about the undo problem with Dropshadows but I am having other problems with Dropshadows as well -- I just haven't figured yet out what triggers the problem. 

If I try to combine multiple objects with dropshadows, it makes a single object and everything looks fine initially, but if I move the new object or merge the new object with the background, all of the dropshadows are simply lost.  This is happening to me very frequently and it is horribly frustrating.  Sometimes I can merge the shadows first and sometimes it doesn't matter.  Sometimes my only choice is to try to copy the object into a new document where hopefully I can merge the shadow before copying and pasting it back into the original document.

However, in the case of THIS problem, if I start a new document, create two objects with dropshadows and merge them, it behaves correctly.  Some other operation causes this problem, and whatever that problem is, it is saved with the image because I can reload a problematic image and the problem will occur every time.  It's not some sort of corruption that occurs only during runtime... I believe the Z-ordering and/or grouping gets corrupted and it is eventually saved corrupted.  In a problematic document, any new object I create will have this broken behavior.

I tend to use groups a lot and I'm not sure if that contributes to the problem.  I encounter lots of problems related to groups over time.  I believe Photo-Paint has problems with groups containing groups in particular.

For example, create objects A and B and group them (A+B).  Create another two objects C and D and group them together (C+D).  Group the the two groups of two objects (A+B)+(C+D).  Click one of the objects and move it.  Only the two objects in the original group (A+B) or (C+D) will move.  The other group does not move even though all objects are actually grouped together.  I can repeat this with a clean document.  Combine this problem with the problem I described in another post regarding dropshadows and z-order, and one attempt to move followed by one undo could mess up your entire layout with no option but to manually correct it or revert to a previous save.

I'm running Corel Photo-Paint 2018 v20.1.0.708 on Windows 7 with an NVIDIA GeForce GTX960, i5-4690, 16GB RAM.