I created a new import template for updating a couple joomla custom fields values. It keeps failing, and furthermore the log shows no problems that I can see and it also will not create a backup of a single template either as a download or saving to folder on server. When I try to backup a template it says it did but it does not. So I cannot give you a copy of the actual template, I made screenshots instead. I have verified the fields I am using are used for Joomla Content and reviewed your troubleshooting notes.
I did not screenshot the options tab for the template, it is just one setting and it is set to NO for keep existing ID.
I have attached a copy of the import file, it is only 4 items. Also a copy of the import log. I tried to download a copy of the template backup log but it says no log available. I successfully updated almost 10,000 articles without issues using CSVI Pro version 7.6.1. This import template was newly created in 7.6.1 but never tested or used until today. I updated CSVI Pro to 7.6.2 within the past week and today was first opportunity to test it works correctly. I successfully exported many files today though.
One of the screenshots shows the onscreen log result after failed import and I think it is saying it failed because there is no fulltext, but that isn't a mandatory field unless it changed? My very first attempt resulted in fail as well saying it required title, so I added it but I thought your docs say for content only alias was mandatory along with category_path and ID of course.
This site was also just moved from staging to live server. I did change the url in CSVI options, and I also tried the import on the staging site which has not changed at all other than the same updates to extensions, and it fails exactly the same way there too. There are no other issues with the site that I can see.
Joomla version 3.8.7
CSVI Pro version 7.6.2
CSVI J2store addon plug 7.6.2
fit-update-test.csv