Hi Alexandre, thank you for reporting this. I want to let you know that our engineers are aware of this and we have an internal ticket with all the details of the behaviour; the blank canvas appears when a complex metric is being computed or when multiple metrics are added at once to the insight.
At this time, I am unable to provide a ETA for the fix, but depending on how critical this is for you, you may also reach out to your account owner @Greta for escalation.