It could be that your systems’ Evaluation Loops are taking more than an hour to complete, in which case this action may not have evaluated during that time. Some of the steps at Tip: Troubleshooting Client Reponsiveness may be helpful.
Usually to implement a scheduled reboot like this, I’d suggest using a task that’s always relevant, and in the Take Action dialog use the day/time/reapply constraints to configure the day & time to reboot
An Action configured this way - that is Applicable, but Constrained until the day/time arrives - evaluates at a higher priority than other Actions that have already evaluated as “Not Relevant”, and are much less likely to suffer side-effects from a long client evaluation loop.