{{trigger.subject}} is not trggiering subject line for AB test email

[Suhail_EK]

We have a campaign set up to trigger the subject link to update Open activity with subject line in MSI. 

But I noticed that {{trigger.subject}} isn't working for email open activity for the email in A/B Test program which i used to test From Email address.

Can you please let me know why does this happen?

[cblack]

I am experiencing this too though I do not have an answer as to what is going on.