That is literally their only suggested workaround. It’s been posted here before, though here’s an exact quote from their CSR, directly from the ticket I submitted:
"After looking into this a bit, it appears there’s not much I can do about this issue. However, the developers are aware of this and are currently working on a fix for an upcoming patch. For now, try to equip the items to mark them, or place them in your bank and mark them there . I hope this helps.
Unfortunately, we don’t have visibility on their progress here in customer support, so we don’t have a timeline for the fix to be implemented. Please follow us on Twitter (@2K, @2KSupport, and @Borderlands), as this is where latest info, as well as, upcoming updates and fixes, will be announced."
That is, per Gearbox and 2K’s official word, the ONLY viable in-game workaround: return to Sanctuary to your bank, or do it in-store. Dynamic comparisons aren’t possible at either, so…enjoy your sorting 
As this is a bug which happened immediately after the Bloody Harvest update, is a known issue, and (unlike other, even worse show-stopper bugs – vide other forum topics, you’ll find plenty), considering there are less than a thousand posts/views on this thread about the issue, I would surmise this is VERY low on their priority list, so I wouldn’t hold my breath for an update/patch for it.
Understandably so, as having BL3 crash your console entirely or wipe out all your saves/characters/inventory are all definitely far worse issues.
As for me…having played the game a little before the Inventory Tagging Bug (made it to Sanctuary3), and then playing it after the update, things went a bit like this:
- First 10-15 minutes: “OK, this is a hassle, but I can deal with it.”
- First mission (which entailed repeated returns to various places to ditch loot, each time taking longer & longer due to the sorting bug (also documented) and the newer Tag bug): “OK, this is starting to suck…”
- After second mission & finding inventory issues were slugging gameplay and making things take at least 2-3X as long: “This is no longer enjoyable, as I’m spending 40-60% of my time manually comparing and sorting trash before embarking on further missions.”
It was at that point I started hitting the official forums up, and submitted official tickets (see any of my other posts here about it).
While I’m keenly aware of the vagaries and setbacks that come with SW & Game development, I’d agree this could have been EASILY spotted by even a few minutes of QA time. As in, any.
Having paid about a hundred bucks early for the SDE, I do feel rather burned…which is a shame, as I really do love GB & 2K’s stuff, and have been a fan going back many years, and I didn’t just buy their PS3 games: I also repurchased many (BL/BL2/BL:TPS, etc) along with the PS4 offerings like BL3 SDE.
So…if you’re feeling burned…join the club. Your choices are to do the above, or play a different game.
HTH,
~J