The channel is still working fine but it may have had a recent change of PID. Many receivers will update fine but some unofficial ones may need a rescan if they arent updated automatically. All fine at this end on a dreambox though.
You could delete the channel then rescan- 10729V 22,000 5/6
I think PID's may have changed from~ Video2338/Audio2339 to Video2340/Audio2341 so you may be able to amend with a channel editor? Not sure what software tools you have available on the tm6900?
just checked and Lyngsat website still showing vpid2338 and apid2339, so checked actual stream to make sure and yes vpid is currently 2340 and apid is currently 2341
You will have to manually change or fully delete it & rescan it.