Looks like the Virtual machine is pointing to Snapshot disk. some time you will not be able to find the the Snapshot details on the Snapshot Manger. you can verify this by following below method :-
Edit settings view without a Snapshot :-
you see the Option for increase the disk is available

Edit settings view witha Snapshot :-
you see the Option for increase the disk is Not available and grade-out :-
you will find the Disk name with 000001.vmdk OR 000000x "X" Indicates the number of Snapshot, below example is for 1 snapshot

if you are not able to see the Snapshot on the Manger take a Test snapshot and perform a Delete all operation.