Personal record for Marathon distance incorrect

I don't run these long distances very often. Today was only my 2nd Marathon. After the first one a couple of month back I already noticed there was something wrong with the record displayed on Garmin connect. So today I made sure I really got the full distance and during the run I never paused the activity and ran from start to finish. Well here is the record shown on Connect.

As you can see it doesn't use the Marathon distance (42.2 km) for the record but instead the time for the longest distance. I remember I got the popup on the watch after the run and it said something like best Marathon with three hours and forty something minutes. 

So I analyzed the fit file on Golden Cheetah and the personal record for the marathon should be 3:47:25. BTW all the other personal records are correct. This issue only seems to occur for Marathon distances. 

Have any of you experienced the same bug? Where should I report this, so Garmin can have a look into it.

It seems like every time you run a distance longer than a Marathon, the connect software doesn't extract the fastest "Marathon interval".