Just making sure that all the boxes have been checked off, before we assume it's a bug.
- You have actually sold all of your exploration data? Your UC unsold data collection is empty?
- If you did sell it, did you happen to get a screenshot of the page where that data was sold? If you were given the credits (cash), then you should also be given the credit (tags).
- You didn't explode at some point in between scanning those systems and selling the data? Data is not retained after death; if you did die, for whatever reason, then you'll have to fly out to those places again to reclaim your tags.
Personally, I always sell my ELW systems individually, rather than have them mixed up in the bulk UC pages. Yes, it does take several hours of scouring through the data looking for those specific star systems (I really, really wish the UC unsold data list was sorted alphabetically, rather than by mass of the primary star). I take a screenshot of the sale price for the system, I then take a fresh screenshot of the system map with my tag on the ELW so I can post it to the ELW thread. Haven't encountered this particular issue yet, nor have I heard of anyone else encountering this issue.