Tags showing unknown quality

I have some tags that are showing unknown/bad quality. These issues occur for two of the same type of PLC (Allen Bradley MicroLogix). I’m not sure why this is occurring. I’ve tried refreshing the tags and importing new tags from the OPC server, but this hasn’t fixed the problem. The tag qualities/values were fine until recently

You’ll have to look at the diagnostics page for that device and the gateway log.