What version of ZCM?
What version of ZSD?
What OS types are not being imported?
Does your Analyze seem to work?
I presume manually kicking off the Import doesn't bring in devices either.

Unfortunately the logs don't express the Analyze process except for 
AMIE: Running Import with cached configuration. This might take a while...
After that you will see mappings for the different components being imported like:
Reading mappings from resource: com/livetime/assetimport/ZDEVICE -> zreference

And less for the Import process.
Double-check that the Items are not waiting to be brought in via the AMIE Snapshot queue.
User > Configuration > AMIE Snapshots

They will sit here if ZENworks Import setting "Auto Create New Items" = No

ZCM version 17.4

ZSD version 7.5

OS Type not imported - any

Analyze does seem to work -- indicates success

I don't think I know how to manually kick off the import (how do I try this)?

Auto create New Items is = Yes so nothing waiting in AMIE snapshot that I can see

Thanks for your consideration and suggestions.

I forgot to mention, I understand that my version of Service Desk is not current.  However the import had been working just fine for a year or so,  now it suddenly stopped working, so I'm trying to find out how to get this working again to continue business processes while trying to schedule time to upgrade to current SD version.

Sorry for the delay.

You mentioned Analyze works by checking the item Categories and then "Analyze" button.
Then  the tabs will display - Hardware, Software, Bundle and Mobile Device (tabs).
Once the selections and settings are made in those tabs the ZENworks Import (tab) will have an "Import" button.
Does this "Import" button appear?
Selecting it should give an information box at the top about "Started importing..." and the Synchronization will show (In Progress).

Please advise if this process is working.

If buttons, tabs, don't display as mentioned above then we'd probably need a deeper look at your system.