We've occasionally received reports from some Pearl Theme users that mention not being able to save WeltPixel Options and WeltPixel Mega Menu options under the Catalog -> Categories section of their Magento Admin. In most cases, the save itself is successful, but the options remain as they were previously.
While this was never something we've been able to reproduce, we noticed that it happens to users who have recently migrated Products or Categories from a different store. It's possible, thus, that there were issues during the migration which prevented certain DB items from registering correctly.
If you're experiencing this issue, you can try the following steps as a potential solution:
1. Remove the WeltPixel_NavigationLinks and WeltPixel_CategoryPage entries from the setup_modules table in the DB.
2. Run a php bin/magento setup:upgrade command to re-create the DB entries.
3. Reindex the store (How to reindex your Magento 2 store from admin or SSH / CLI) and flush the Magento Cache from the Cache Management section.
4. Check the save functionality again and assure the settings are applied.