For example, take a look at the data of a 2x2000 interval session from ERG Data (it's in Italian but I think it's clear anyway):
Interval 1 --> Avg HR 156

Interval 2 --> Avg HR 160

These heart rates are consistent with the raw data I see from the CSV file. So I would expect the average HR for the whole session to be around 158.
Here comes the first issue: interval table still from ERG Data. Average heart rates for the single intervals and for the whole workout are completely different (and wrong):

Here comes the web logbook. Heart rates for the single intervals and the whole session are the same as ERG Data (the wrong ones):

Am I missing something? Thanks