Uncertain initial value

I have a digital tag from an OPC/UA device (advantech adam-6317). when I edit Tag Group from 'default' to any other group the Value shown in the tag browser shows "Uncertain_InitialValue". i need this tag to be polled faster than 1second. it doesn't matter if I make the polling rate faster or slower. same result.

Is there anything obvious shown in the Tag Diagnostics? Are there any differences between your Tag Group and the default one, besides poll rate?