Panel Table - Join queries don't work because different timestamp


We have grafana 6.7.2 and encounter a problem with the join queries in table panel.
Two print screen to a better look:
when my system time is not synchronize

when my system time is synchronize

There are 2 requests in my panel and the difference is
certainly linked to the timestamp of the query. That’s instant queries with prometheus datasource !

What do you think about that ?