If you update to Joomla 3.8.10, please make sure that you either do a full GitHub update of Fabrik, or disable caching for your lists (in the Advanced settings) or turn off Joomla's System Cache setting. A change in Joomla's cache code in 3.8.10 required a fix in Fabrik, which will be rolled in to the next release, but is currently only available in GitHub.
Problem with Kunena 3.x
Fabrik3.x and Kunena 3.x.
1) Install latest Fabrik version
2) use phpMyAdmin (or whatever), find the "Fabrik - System" plugin in the #_extensions table, and set 'ordering' to -1.
3) Empty Cache (site and administrator by FTP - I had only index.html file on each cache folder )
4) Install Kunena 3.0 package