sorry for a late response. Could you please post here a print screen of your ARC and TRND blocks properties? I assume that you have RexArc installed on your device with command sudo apt install rexarc
and you export data from the archive to CSV using a command in RexArc (please, correct me if you are using different approach). Could you please copy this command as well?
How much difference is there in time stamps? Can't it be caused by a wrong set time zone? In the ARC block, there is a parameter ldaymax. This parameter set the maximum size of archive per day (see doc here. This could be the reason why some data is missing.