Data Merge - Can't preview without errors
The apparently long-running Data Merge previewing error!
Occasionally previewing a data merge will permanently ruin exports. The only solution is to create a new document. Happened to me on almost every project I tried - wasted hours and hours.
See this thread and video for more information:
(Also colons in csv titles makes file unusable??)
Paul Nylander commented
I've found this error occurs if I have other page elements, such as a footer in the master page.
And, yes, as of 2022's Id 17.4, this bug is still present.
Same here, data merge would not work on ANY existing document, but worked flawlessly on a new document w/o formatting.
This does waste hours, previewed early on and spent a ridiculous amount of time assuming my files weren't set up correctly when it was InDesign the whole time.