Unable to delete previous versions of a vdisk after merging to a new base.  No Target devices were using those versions but Delete was greyed out.

Customer created another merged base and then made a copy of that vhdx.  They then imported that as a new image and assigned all targets to it.  Once all targets where off of that image, they were able to delete the the versions from newest to oldest including the versions that were greyed out before.

Problem Cause

Specific cause unknown but it appears as though when a new merge base was created, the previous versions were not flagged as no longer needed.