Can you post your Actions so we can test cc 2018 with them? We have no idea or what Photoshop step they do.
They are skin smoothing actions-- using a soft white brush to smooth skin. They were purchased from a company and are copyrighted so I don't think we can post the files. We reverted back to 2017 and they are working perfectly.
All I can suggest then is to single step through the actions and see what is failing. Actions have dependences. If the document does not meet them actions will fail normally with a message like command is not available or not in this version of Photoshop.
You can not post the actions so you must find our what step is failing.