Stats of TUs added to TM in TM statistics and Update report differ

Question

SDL Trados Studio 2015 SR2 - 12.2.5141.6 Windows 7 Enterprise SP1 
 When comparing the "TUs added" in the Update report of a project with the "Translation units added since:" in the "Fuzzy Index Statistics" under "Performance and Tuning" of the TM settings, I noticed that most of the time the numbers didn't match although the TM stats had shown "0" before the update, i.e. the TM had been reindexed before. 
 Is this normal behaviour or a bug? 
 I haven't tested yet which numbers are correct based on the total number of TUs in the TM before and after, but it means that this information isn't reliable to establish any kind of reports or statistics.

Paul · Accepted Answer

Hello Raphaël, 
 
Perhaps the difference is because the analysis is reporting on the files and the Tm is reporting on what actually went into the TM... very often this will be less because it will strip all kinds of things out as separate TUs; number only segments, duplicates, placeable only segments etc. 
 
On the face of it I think this is normal. But without seeing the data and making time to do a proper analysis I can't really be any more confident than that. 
 
Regards 
 
Paul

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Stats of TUs added to TM in TM statistics and Update report differ