Timelion extremities not showing

Timelion data is not showing properly. I feel it's an issue with UTC vs local timezone but it's not only that. I did change my local time zone to UTC without success.

When selecting a 24 hours time range under the "absolute" tab of the date picker , the beginning and the end of timelion's graph is blank (24h):

But there's no gap of that sort in my data (~48h):

kibana=true in the timelion expression.

It seems I always get a little bit of missing data, it's just more obvious as the time range shorten.

Kibana 6.6.1

The moving average is causing this issue. It's either a super spiky graph or a smoothen one with blanks. Any idea on how to improve that? Thanks