Missing some data on an external training report - for some rows only

Summary

We have a report on external trainings that retrieves custom field values for some rows only, although we can see the missing ones on the transaction screen

Content

 

Hello,

We have this report below which runs fine (leave all the parameters blank or wide), and it seems to work fine, but it doesn't retrieve some of the Cost or Provider information for all rows.

Some rows are fine, some are missing. We can see on the online screens that the missing data is in the system, it simply doesn't appear in the report. Would you have any pointer or test ideas? Is that a known problem?