Hi Tacia,
The visid_high & visid_low columns are based off the 'aid' value. Deploying the MCID service can change what you're seeing in data feeds, but it doesn't control that column. Below are a few scenarios that you might see:
Scenario 1
MCID service deployed with grace period activated (New or Returning Visitors)
Result: You're hit would have a s_vi cookie and therefore an 'aid' value. This means you should see values in the visid_high & visid_low columns
Scenario 2
MCID service deployed with no grace period activated (New Visitor)
Result: You're hit would only contain a 'mid'. This means you should not see values in the visid_high & visid_low columns
Scenario 3
MCID service deployed with no grace period activated (Returning Visitor)
Result: You're hit should contain both a 'aid' and 'mid'. This means you should see values in the visid_high & visid_low columns
I know in your post you indicated the page had both a 'mid' and 'aid". Have you verified that those hits have an 'aid' do not have a visid_high & visid_low?
Thanks,
Jantzen