I've had the same happen to me. There should be 3 polls attached to every upcoming (and newly created) meeting but they've suddenly disappeared after working fine for several weeks. I can't find anything online to help.
According to the May 21st Release Notes, there is now a checkbox on the Admin side that will need to be enabled. This is no longer enabled by default:
Allow or prevent users from managing saved polls and quizzes If polling is enabled, account owners and admins can enable or disable the ability for users to manage their own saved polls library. Previously, this was enabled by default if polls were enabled.
Check with your account manager to confirm this is enabled. Still waiting to find out if previously added polls were maintained or lost...