Do you see any Warning message on the preview screen which says "You do not have required privileges to preview the data" ?
Please see if any of the below KBs are helpful:
Also check if this license is availble "Midstream Data Preview License"
When you said you started seeing this issue post upgrade, are you referring to July 2021 upgrade?
Thanks for the response Rakshitha.
I tried to post screenshots in initial post but seems they did not work. I also cannot attach them because png and jpeg are both forbidden apparently. If screenshots would be useful please let me know and I will try again.
Yes we have the Midstream Data Preview License, I see this in Administrator.
We also have Data Previewer role with the correct option selected and a user which has both this role and a Data integration Executer role - I can run mappings but cannot preview data.
We do not get an error message because Data Preview tab is not present in any of our transformations.
We did previously have this access but even these specific mappings that we definitely used Data Preview on no longer have the Data preview tab on any of the transformations.
I am unsure exactly when we lost this access unfortunately, could be that release or a few months before.
Please share the screenshots on how the data preview option is seen in your mapping.
That might help me get some idea on what could be the issue.
Thanks for the support on what turned out to be a silly question Rakshitha.
Seems the data previewer license was attached to a trial Edition which had expired and I was misreading the administrator.