Multiple run-ins with this issue throughout one game during two rounds or so.
With regards to the screenshot, bomb was floating and no-one on the team could pick it up. It would display the progress bar when taking action with (by default) the “F” key, but would infinitely loop if you held it with your reticle on the bomb. All teammates were unsuccessful with picking up the bomb, with the exact same results. Occurrence was at the beginning of the round where the bomb had yet to be spawned to someone, and instead chose to be demonically possessed.
Image: http://i.imgur.com/rItml3R.jpg
Does not seem to be a way to replicate it, although our Bushwacker (changed to Aura in screenshot, I believe) had an issue last round and was consistently given the bomb all rounds previous. Possible relation to this error? http://forums.dirtybomb.nexon.net/discussion/21431/execution-bug-c4-not-getting-recognised-as-planted#latest
Bushwacker’s issue last round was apparently being unable to plant the C4 on the objective, details were not known. He just kept going “wtf?” about it in voice chat and I couldn’t get any evidence as such, apologies.