Static leases stop being handed out after 4-5 days of uptime. Dynamic still works, no data on fail in dnsmasq.log

[loughkb]

I'm running a fresh build of 3.5.5 and I'm seeing a problem that I also had with 3.5.4. After around 4-5 days of uptime, devices with a static lease configured in the router will fail to connect, hanging on getting an IP before timing out. Devices that are setup to be dynamic will continue to connect and get an address out of the dynamic pool.
Looking at the dnsmasq.log file, I only see activity when the dynamic devices connect. No request is logged for the devices with a static lease defined.
Rebooting the pi gets things working again for another 4-5 days. When it's working, both dynamic and static leased clients show normal activity in the dnsmasq.log file. When it fails, only the dynamic devices show in the log.

My workaround for now is a root crontab entry that reboots the router at midnight on the 4th day.

I've looked through the docs and the FAQ and not found anything, my apologies if this has already been reported.
Kevin