Same issue as the images sent in the above thread by dilipborad . D.

All activity.  And it only shows comments.  If I change the record... it used to 'record' it in the activity.  And I created a new record .. to ensure this wasn't because it was an old record. 

Did you ever find a resolution for this?  We are having the same issue.    And these aren't even old records.  I can create one today.. and any field I change (it use to be in my acitivty history) is not showing up.  Only comments.  D.

I am also having the same issue.  And this started to happen in November.  I noticed the plans (which we pay for)... changed names around that time.  Did they also restrict history???  Any change I make current (not even past records) are bring recor...