Issues can always arise. With our paid plans, support is included. But this only works out for us both, if sufficient basics are covered first. This page and subpages include handy information when troubleshooting things yourself.
We update our extensions very frequently. With that, if there is a bug, the first thing we will often ask you to do is to upgrade. Every module is released with a CHANGELOG.md that you can review beforehand to check if the fix you need is included.
If you are not keeping your modules up-to-date, the first thing we need to know is which module versions you are using. You can install the LokiCheckout_CoreAdminhtml module to allow for showing a list of modules in your Magento instance and whether a new version is available or not.
Also, on our site, you can always retrieve the latest module information. You can cross-match this with the modules you have installed. From the CLI, analysing your composer.lock becomes easier if you are using the tool jq:
cat composer.lock | jq '.packages[] | "\(.name),\(.version)"' -r
The LokiCheckout_CoreAdminhtml module also offers a System Check page in the Magento Admin Panel with common configuration issues. Review it to make sure all checks are green.