I came across two wooden crates. I could not pick them up, or interact with any of the items inside. I tried many things, some of which are shown in the video attached, but not all. Here is a list:
Tried picking up the crates with the F button as normal
Tried dragging items out of crates onto the ground
Tried swapping items in the crates with same-sized items in inventory
Tried swapping the clothes items in the crates (plate carriers) with clothes items on body (stab vest)
Tried logging out and logging back in (same result)
Tried double-clicking on each item with empty hands
Tried shooting a crate but not destroying it
Eventually since I couldn't fix it, I destroyed the crates with a shotgun and the items inside went away. However, not too long after this, I was able to interact with other wooden crates inside my base just fine, suggesting this was an issue with these two crates in particular, not wooden crates on the server in general. This was around 9pm US Central Time on server 4403, by a building in between Novy Sobor and Stary Sobor. It looked like a player or players had just been killed there, as someone had chopped down a nearby tree, and probably built the crates to stash the player's items. I also heard shots not too long before coming across these crates. I wonder if it's possible a hacker locked the crates somehow. I was still able to interact with the human meat and other items that were left the ground outside the crates.