So sorry to hear this has happened to somebody else
Happened to me when I was out at Beagle and 2.1 dropped;
https://forums.frontier.co.uk/showthread.php?t=260061&p=4020334#post4020334
I also contacted support and unfortunately, never did get a resolution [there was talk of a missed 'process' as one point, then wait for next patch and also talk to QA....but it all went quite and shrugs]. I did find I could sell all the data, but it made no difference to me being able to see the systems, which included my first undiscovered ELW. If it is any consolation, I revisited my ELW and found it was indeed tagged by me, yet I was able to sell the information *again*.
I see yours is slightly different because you can see the stars where as I couldn't even get the system map at all, so hopefully yours is rectifiable. Regardless, I'm pretty sure your tags will be safe. Good luck o7.
I'm about 15KLY out of the bubble and last night I noticed that the servers were a bit wonky. System honks would result in only seeing the main star on the system map initially and then when I returned to the cockpit after a few seconds I would get the notice of several items discovered, re-open system map and see it properly populated.
Not sure if it's related, but the servers were a bit off lately.
I checked one of my old systems that I tagged long ago just for fun that had 100 objects in it and all is well.
Hopefully it's just a server glitch that will resolve.
I must be dense, did you never turn in the data until after 2.3 was released?
So 2.whatever -> 2.3 out in the black.
2.3, you return, you sell data, but everything from pre 2.3 is lost?
I have seen this happen with my data too only to have it magically restored later. Try not to worry about it.
All the exploration data is stored on the server, hopefully support can restore your account access to it.