Hi Dominique,
The github repo is the right place for bug reports. Much of the team was out for December holidays, and your report should get looked at as people return to the office and work through the backlog. It should already be on their radar, and I'll send a reminder just in case.
If this issue is time critical for you (presumably not, since you're running a preview version of Xamarin Forms) then you can open a support case to get eyes on it sooner.
Note that Nicole's suggestion was for others to comment and vote up the GitHub thread to help prioritize, not to vote up this thread.