There's several things should be taken in care for uninterrupted log collection:
1.You can't change your static ip configuration of your logserver, 2.You can't change your Logging Rules/Actions of your mikrotik router, and in case if you change, your log server static ip and logging Remote Address should be same,3.Log Server should be always powered on.
There's several things should be checked: 1) Check firewall rules from your Mikrotik server. 2)Check your Logserver's static ip, and check your Mikrotik logging action fields and search for Remote Address ip. If these ip's aren't same, you won't any logs. 3) Go to ServiceInfo page and check if Rsyslog & Mikrotik services are running. 4) Ping your LogServer from Mikrotik router and check if routes are okay. 5) Check your storage if disk is full