When compacting large datasets (> 40 million rows) the percentage done and progress bar fail to display the appropriate % done value, as shown below
Compaction tool run as part of a model, note the percentage done is saying 100% , yet only 42 million out of the 48 million rows are processed
The same issue occurs if you compact a geodatabase from the catalog panel, see it says 100% done yet only 65 million have been processed.
This is occurring in 2.6 and 2.7 of ArcPro.