This may not work for everyone but this is what I did and it worked. I have POS 19.0 Pro Level and QB 24 Enterprise. I had this issue with QB 23 once in awhile but after the 24 update POS 19 and QB 24 would not sync. 

You will need the Quickbooks tool hub program installed. Open QB tool hub and select network issue. Click the green icon that says "Quickbooks Database Server Manager" . You may have to browse and add the location of your company file folder, Mine is C:\Intuit\Quickbooks\Company files. once you add the correct folder then hit scan and all the files that should be shared will come up and POS 19 will be able to sync with QB Enterprise 24.