My 735XT has stopped sending my VO2Max and FTP scores to Garmin Connect

My watch seems to be recording my VO2Max score perfectly well. I check it via the menus on the watch itself every couple of weeks. However, I recently looked at the VO2Max part of the

"Performance Stats", on Garmin Connect and was surprised to see that, although there was a record there of my score for the first nine weeks that I've owned the watch (from late January through to 25 March this year, after the entry for 25 March, there is nothing at all recorded. I sync my watch with Garmin Connect once a day.

My figure for lactate threshold is updating, as is the "training effect" figure for runs I have done. While typing this question, I've noticed that the FTP section only shows two entries - one for around when I bought the watch, and one for about a month later, but nothing since.

Surely this data should be updating at every sync session, even if the figure is unchanged from the previous occasion? Grateful for any comments and suggestions. Thank you.