::uniques_exceeded:: values being imported

[#1]

I've set up a connection between Power BI and Adobe Analytics, and I'm importing some data from a specific segment created for this study. The segment is created using Page URL, and it is at Hit level. One of the fields is the Visitor ID. However, some of these visitor ids show up as ::unique_exceeded:: or ::unspecified::, as you can see in the following image:

Is there any reason for getting this error, or is there a way to get rid of it?

Thanks!

[#2]

@marcos_henrique_casc  This is due to Low traffic logic Adobe build on reporting. There is unique value limit for each dimension in report suite. Once the unique limit exceed for a dimension, all values getting collected shows as unique exceed in reporting. However, you can pull data warehouse request to get the actual values being captured. 

Unspecified line item means, value for the dimension was not present when hit was received at Adobe servers.  

Refer the below help document for more details on logic of unique-exceeded or low-traffic :

https://helpx.adobe.com/si/analytics/kb/uniques-exceeded.html

[#3]

I do not recall the exact number but Adobe variables are limited to around 500,000 unique values per month unless you go through client care to get the number bumped up to a max of 2,000,000. I would imagine this is related and is similar to the Low Traffic values that are seen in the reports. I am unsure about unspecified in visitor id. Perhaps calls are getting in without the visitor id service or you are using your own id and mapping into visitor id and it is null - not set?