(Lots of) files are "not erased" (recuva) but missing in explorer

Hello,

I just plugged my passport external drive as usual to grab a file and got shocked like never when i realised few folders (containing a lot of files) were missing. I immediatly used "Treesize" to see where these were and to my surprise, they do not appear anywhere, even though the reported remaining space include them..!!

I then launched recuva, expecting them to appear as erased (even though i never did) but no! It shows them as "not erased".. Why is that i can't see them in such case?! I thought about recreating the main folder (let's say it's called XX located in root) but i'm afraid that'll make things worse.. Never seen nor heard about such case before.

Please help!

Seems like somekind of structure issue but i have no knowledge/experience with this. There are dozen, even hundreds of subfolders and the files are huge.. It's a matter of terabytes in the end. Recovering them one by one (folders) would be hell. I really hope there's a solution with this. I did not do CHKDSK yet, afraid it'll make things worse!

Before you do anything major to the drive like chkdisk or defrag, or just writing to it.
check to see if they show up in explorer with the options to show hidden files checked
and the hide system files unchecked.
download minipartition tool to see what's on the drive and maybe if there is anything wrong with the partition.
upload a pic of it if you can.

I did have all hidden file shown already. I can't access the main disappeared folder even by typing its name in address bar. As said earlier, it does not show up in SpaceSniffer or Everything, even though it's taken in account in the total occupied size. Same issue on any system where drive is plugged. However, as said, RECUVA does see the files.

I did recreate one of the missing folder and shockingly i wasn't told there's already one with that name, it was just created and it's empty.. Now when doing a scan with recovery software, i can see the new empty one and the old-full-missing one.. I read that CHKDSK is the only thing that COULD POSSIBLY bring back the folder. But it could also mess everything, putting all these files in a FOUND folder, renaming them in a crazy way.. Correct?

Did you try mini partition tool?
It may show if there is anything wrong with the drive.
It also includes data recovery.

I have tried many but not this one. Please be more specific, what do you want me to do in it?

Attachment 233115

you can click on the drive and a great deal of info there . the folder maybe recoverable.

..? If you read my post again, you'll see i mentioned content IS RECOVERABLE. I would just like to avoid this, due to the amount and size of actual data. I may not even have enough free space on spare disk.. Anyway, in this app partition explorer, data appear but instead of having the folder named +XXX (original name), it is shown as _XXX~1. Sub folders are however named correctly. So it seems the issue is with the main folder. Isn't there anything else to do than data recovery + chkdsk..?

Sorry, This has reached my limit of knowledge, I haven't encounter a situation quite like yours.
Hopefully, one of the gurus here have and can advise you further.