Things are working fine for me (EU868 with the MQTT Data API). Also, nothing specific on the usual channels from The Things Network Status Page [HowTo].
What’s that “datalog”? Where are you seeing the incomplete uplinks? What are you seeing exactly? Can you confirm that the devices are actually sending? (Of course, seeing 4 of them fail simultaneously would be rare.) What interfaces (MQTT, some integration, …?) are you using? Which region? Do you have access to a gateway and if yes: what’s its Traffic page in TTN Console showing? Any screenshots of the application’s Data page?