
Is it a bug?

Is it a bug?
Probably an out of sync Hive node. Can you try switching to a different one in your settings?
I tried
rpc.mahdiyari.info
api.openhive.network
api.hive.blog
hive-api.3speak.tv
But still the same error. Normally is set to Auto
I was able to support the previous proposal
Are you using Keychain? What happens if you try to vote directly from this page?