Pie Chart representation disappears when adding a Multibar Graph Panel

[davidfa94]

First of all, I saw there was already an existing closed issue #7 describing basically the same problem, but, since the bug has come to me again in a newer Grafana version (v6.5.3) and it has a slightly different behaviour, I have decided to create a new issue.

When I create a Pie Chart in a dashboard, it looks normal:

However, when I add a Multibar Graph Panel to the dashboard (it doesn't even have to hold any data, as you can see), it gets bugged like this:

Then, removing the Multibar Graph Panel fixes the Pie Chart (but ONLY if I exit Grafana and enter again).
Furthermore (and only if I don't exit and re-enter Grafana to fix it) the Pie Chart gets bugged even if I create it in another dashboard:

I hope we are all good during these difficult and busy quarantine times, so any effort to tackle this issue will be highly appreciated. Stay safe.