Troubleshooting: Line Items not Saving
Line items not saving, or removed after the invoice or estimate is saved:
There is a bug (or incompatibility) with Jetpack 5.1+ and servers not running at least PHP 7. Please downgrade to your version of Jetpack if possible, or upgrade your server's version of PHP7.
There are reports of things being resolved after JetPack is deactivated and reactivated again.
If you have any additional information for Sprout Apps to troubleshoot this please send a support message.