Another thing worth checking is whether UDFs are enabled on your server. There are some RDs that fetch non-exposed columns and will not work properly if UDFs are disabled. Quick check - Do private edit of pxGetFeedbackRecords RD and see if you are able to save it. If not, remove 'pyFullText' entry, Save and then see Training data tab.
Thanks for the reply. I think the issue got resolved. Here is what I was doing and what I corrected. Please review and confirm whether my understanding is correct or not.
1) Configured Email Channel to process emails of firstname.lastname@example.org account.
Scenario where email won't be visible in Training Data
2) Email is sent to email@example.com, Pega creates Triage WO(Work-Channel-Triage-Email), this triage WO gets resolved automatically if any of the intelligent routing conditions is true. Before I was thinking that this email should be visible in Training Data which is not the case :( , now my understanding is for emails where Triage workobject is resolved automatically, those emails won't show up in the training data as System was able to process them successfully.
Scenario where email will be visible in Training Data
3)When email is sent to firstname.lastname@example.org, Pega creates Triage WO(Work-Channel-Triage-Email), this triage WO won't be resolved because it doesn't meet any of intelligent routing conditions, in this case this case has to be processed manually and will also show up in the training data as system was not able to process this Triage WO successfully.