There is no link between the 'Pack' and OFS.
When a 'Pack' is recommended, 'MEM' is displayed in red in the status bar of Unity Pro. (Indeed, the memory becomes fragmented after Unity modifications and sometimes a Pack is required).
The 'Pack' needs to be done in connected (Run or Stop)
The 'Pack' doesn't modify the XVM file.
Indeed, the 'Pack' is done on the Physical Memory, not on the Logical Memory ; so all variables (located and unlocated) keep their addresses.
On 'Pack' the Physical Memory is changed and OFS is not impacted (whatever the Consistency configured : Strict or Debug) because the Logical Memory (e.g. unlocated data) is not changed.

E.g.
In Unity, add / delete unlocated DFB instances (which are included in the User Data / Declared Data as seen in the Memory Usage screen).
In OFS (Server and Client), there is no Bad Quality on these unlocated data during and after the Pack.

Copy/Paste of the Unity Output window :
"Packing PLC Memory...
Downloading and Executing On Line Changes...
Process succeeded  : 0 Error(s) , 0 Warning(s)"