Not sure which additional confirmationyou may need, in the logs maybe? Unless there's an inconsistency here, logs and UI would show you the exact same information, that is either fast clone is used, or not. I've already experienced a couple of scenarios where fast clone was not used, and as Anton said, they both showed that not all the conditions were met.
For example, once we had to reformat a volume originally created with 4k clustes, with 64k. After we moved back the existing chains into the volume, the first weekly synthetic full actually failed to leverage fast clone. That was totally expected, since by moving the files with regular file explorer copy/paste operations, we actually reset any alignment of the custers. That synthetic full got created as a ful blown file, and only after another week we experienced the fast clone on another synthetic full creation. At first sight, you may have said that all the files used in the first synthetic had been created by VBR 9.5 , but in reality they have been "created" by windows explorer. Only after a week all the conditions had been met. (also because the file were previously aligned at 4k, so the alignment had to be re-done for 64k).
EMEA Cloud Architect @ Veeam Software
Veeam VMCE #1