Some Files cannot be transferred to My Pending Files (V3.0.14.276 x32)

I used to be able to move files including those from the system32 directory to my pending files so that I could do a lookup on them. I can move some files there, but I cannot do that with other files. I.e. I tried moving a few files that reside under c:\windows\system32. and I get a quick pop-up which looks like it is being moved, but the file never appears in ‘My Pending Files’. WMIPRVSE.EXE, CLEANUP.EXE are examples of files that cannot be moved to My Pending Files.