I've posted a beta for the 2.2.0 PTR. This beta will only work on the PTR right now, do not try and use it on live. Since there's no way to post a version here without making it the default download I've only posted the beta on curse. You can find it at:
http://www.curse.com/downloads/details/8064/

Feedback is appreciated either here or curse.

This is either a new issue which I can't replicate or... You're not running my version and are running Talos' version. There was an issue like that with his version because of a change in the way cooldown frames were done with 2.0. He missed a spot to change it. The very first version I put out fixed this.

Alternatively, if you're running tbag on the PTR this is a known issue. 2.2.0 changes a ton of stuff with respect to bags, the posted versions of TBag are not compatable with the PTR. I'm working on a version but it's not possible to make one comptable with 2.0.0 - 2.1.0 and with 2.2.0+ so I have not released it.

If it's neither of these issues can you move things around in your inventory and see if you can figure out if it's specific to an item being in a certain slot or something? It's possible there's some other bug that I haven't seen yet. Unfortunately, without a way to replicate it, I'm going to have trouble fixing it.

Only thing I can think of like that at all would be when you just receive an item it doesn't show up as fast as say with the default UI in the bags becuase TBag has to figure out where to put it and also TBag auto-stacks.

If the above isn't what you were experiencing then some additional information would be helpful. Was it a specific item or type of item. Was there something specific you were doing when it occurred?

One thing to note, TBag (and every other bag code) uses the Blizzard code to display and interact with the items. So it's very improbable that an item will get lost or not display due to a TBag problem.

Basically all TBag does is makes copies of all the buttons in the bags, then moves them around to organize them.

No it wouldn't. I don't believe any addon can do this as setting files are segregated per account.

- Fixed: When the bag or bank is closed in edit mode and then
reopened the edit mode button text would be out of sync and
say view when it should say edit.
- Fixed: When viewing inventory of another character, the bag
icons would sometimes revert to the current character's bag
icons.
- Moved the dropdown, search and various buttons at the top of the inventory and bank windows to the left side and
reversed their order. This avoids the user drop down menu
from cutting off the screen when a window is positioned at
the far right of the screen. Really only had to move the
user drop down menu but it looked bad if I didn't move the rest.
- Fixed: Clicking on bag slots when viewing another character's
inventory will no longer pickup items on the current character.
- Fixed: Lua error when shift or ctrl clicking an empty slot
while viewing another character's bags or bank.
- Fixed: TBag would remove character specific keybindings on
the first run.
- Fixed: Lua errors when mousing over a bag slot that had
no bag in it.
- Fixed: The FluidFrames addon would prevent the right click
menu on the inventory or bank window from coming up and
if you moved the inventory or bank window it would not
remember it's location.

- Fixed: Ability to split stacks in bank.
- Fixed: Backpack button not opening inventory window.
- Fixed: Bag spotlights weren't clearing when closing inventory
window in some cases.
- Fixed: Other mods using OpenAllBags() were causing the blizzard
frames to open. BulkMail2 was an example of such an addon.
- Fixed: When the Keyring is set to show in the inventory window,
clicking on the keys allows you to properly interact with them.
Previously, you'd pickup inventory items rather than keys or
nothing would happen.
- Fixed: /tinv show, /tinv hide, /tbnk show, /tbnk hide were not
working. Fixed them.
- /tbag is now an alias for /tinv.
- Shift clicking on bag/backpack/bankbag buttons now produces a
consistent result. In particular shift clicking on the backpack
button will no longer close the inventory window.
- Removed the Talos from the header on the keybindings.

- Right clicking on an item in a built in bank slot wasn't moving
the item to the bag. Somehow the frame wasn't inheriting
the proper events, added them back in.
- Hopefully fixed the stacking problem where the item would get
stuck in the cursor. Stacking is still somewhat slow but it
shouldn't get stuck anymore. Removed the issue from the
Todo/Known issues list.