This may be due to the server trying to keep up with everything but here is what happened.
Successfully filled a blood bag from another player (indoors) placed the blood bag on the ground so he could pick it up and it seemed to vanish. I had placed my medical kit on the ground a few moments before and it was fine.
The specifics of where it was is below in the steps.
Walk into the left apartment building (when facing away from the main entrance to the north Cherno hospital.
Go left again into the room with the L shaped couch.
Place full blood bag on the floor close to the corner of the couch.
Thanks for your feedback. This is a known issue and a duplicate of #0003292 (When dropping loot it sometimes disapears forever).
Please use the search function to check if an issue already exists before posting a new one.
Refer to the original to provide additional information on the issue.
Regards,
Johnny