WARNING!! I had to send my driving license off for the address to be updated. I got my new one back no problem within a couple of days. I was in Hein Gerike getting a new lid on Sat and told them how quick it had been. They asked to see my license and gave a sigh of relief when they saw it. It seems that the DVLA have been sending replacement licenses back without the bike entitlement on it. Then the person has to re-sit their bike test to get it back. The guys in Hein Gerike in Preston said that they had seen this more than a few times. There advice was to photocopy your license before sending it off.
I've heard about this to !! Seems like madness that they can do that and then you have to resit your test. I had heard that even having a photocopy made no difference but no idea whether that is true or not ! I had to send mine back the other week and the first thing i checked was the bike entitlement, maybe stick a note in with it pointing out you have a bike license
My license is due for renewal next year and have already taken measures to make sure this doesn't happen, I have scanned both the green and counterpart of the license and have saved them to my laptop also I have made copies of them, When I send it off to the DVLA I will be pointing out my driving entitlement and inform them that copies have been made so any missing entitlements will be challenged, Although this a rare problem it does happen as you have said and I have also read about this problem in a past edition of MCN so make sure you take steps if your license is sent to the DVLA. Remember they don't always get it right
This weeks MCN have a page on the subject again, even a police rider has had his entitlement wiped off