Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
I have the same issue and it happens for no reason. Some polls work, some doesn't.
What I do is to create the poll or reply with a poll, pick the options and attendees and just before sending I make sure I can go to the poll using the buttton "view your poll" and then I make any change, like moving one attendee from optional to required or remove an extra time option. If I can go to the poll and change something I know it was created correctly. If not I cancel the f* thing and start over.
This is no fix, but at least you know people will be able to vote when you really send your email.
This happen to me at least 1 in 10 polls. Searching the internet you can tell thousands of people in corporate environments (not free customers) are having the same issue for several years now and MS has not fixed it yet.