I'm having essentially the same problem with VMware Player 7.0. The procedure that used to work in previous versions to compact a VMDK after zero-filling it, is now not working. When I hit "Compact" essentially nothing happens, where before I would get the zero-filled space reclaimed and the VMDK file size reduced accordingly. I think it must be a bug.
It's been difficult to find anyone discussing it because in almost all instances turned up by a web search where people complained about VMDK compaction problems, they weren't zero-filling first so their problem was their own lack of understanding of the proper procedure, as opposed to this new bug.
Edit: Downgrading to Player 6.0.4 from 7.0 restored the normal compaction capability and allowed me to complete my normal compaction procedure successfully. So this would support the hypothesis that the compaction problem is a bug in 7.0.