Reach out to support. On my case, there was something strange going on in my database. There were strange symbols that I couldn’t see in Excel, but after calling support they told me to use either Notepad++ or regular notepad. I used regular notepad and manually deleted the special symbols, and tried to import it again and it worked
We had this issues as well, and through a lot of trial and error, figured out that certain characters were not allowed in any of the columns. Specifically, "&" was tripping up our import.
Having this issue currently, strangely in my companies instance as well as in the training instance when I was taking the Concepts I course this week. Waiting to hear back from support.
This is by no means a permanent solution, but the list import worked for me when I used a different browser.
Here are the troubleshooting steps Marketo support provided me:
1. Check if the file does not have any empty fields. Please update them with the value "NULL."
2. Try clearing the cache and cookie of your browser.
3. Try using a different browser.
Thanks Nikhin and Nick, tried a different browser and it worked (even with characters!) Fisdled with some chrome extensions and everything works fine now!