In the past there have been complaints of some RIP44 packets not reaching their destination, enough so that routes sometimes vanish from the RIP44 table on the receiver. Although there is currently little I can do about packet loss on the network, I have slowed down the rip sender by 100 microseconds per sent packet to avoid saturating buffers on busy networking equipment and thereby avoid causing possible congestion loss. This means that it now takes a little over a second to send the complete set of (currently) 26 RIP44 packets to each of (currently) 435 gateways.
I don't know if this was the cause nor whether this will help, but it's a cheap fix and it may help. Slightly slower packet delivery shouldn't negatively affect anyone.
RIP44 transmissions are still sent every five minutes. - Brian