Please make sure and confirm if you have the installed WmDeployerResource package installed on the v9.8 servers and see if you were able to connect it from Deployer IS/TN and if that doesn’t exist try to Install it from the 912 Deployer for those sources.
I believe if you confirm WmDeployerResource package installed across all your wM versions and use WmDeployer912 you can definitely promote the packages backward compatible from Source 9.x packages to target 912 via Deployer9.12.
Please check the current setup with your admins also and capture info from the logs.
Alternatively time being, you can follow as Mahesh suggested using replicate folder options.
There is a table which lists all version compatibilities. Hope this answers. (Note: I have not tried this myself due to the setup but this should be true)