Hi kemo,
When you say 'Anytime I tried through YEM my files are greyed out and cannot be selected' do you mean that the UVD files are 'greyed out' in the selection list that appears when you use YEM to import a pack?
If this is the case, then it is because individual 'UVD' files are regarded as content by YEM and are not included in the list of file types to import as a pack. The 'UVI' file type is included in the list so you should be able to select this and the pack along with the associated UVDs should be imported. (actually I've realised that UVDs or UVNs won't be listed at all from this selection box)!
However if you mean that the UVD files are 'greyed out' in the selection list that appears when you use 'Import Content' to import them into an existing or newly created pack, then I'm not sure what is going on because as far as I know, you should be able to do this!
If instead of any of the above, you mean that you have been able to import the pack into YEM, but the 'check mark' (Tick) in the pack icon is 'greyed out' when you select an 'Install Target' to make a '.PPI' to install to your keyboard, then you should be able to 'click' on the pack icon and the check mark should turn green, listing voices/content from that pack in the lower part of the screen and allowing you to select them to include in the PPI.
Regards
Ian