Unable to replicate your issue in v13.37 here.
Programmed audio fades at the head and end of a project, and at the head and end of clips.
After saving and reloading the project, all fades were intact.
Under OPTIONS | DISK tab, Clear Unused Cache Files, then load the project.
You might also test the current release. For licensed users upgrades are free for up to six months from purchase date. After that, VP will continue to fully function but a fee is required in order to register the newest. Retain your old install file and registration info. If there's an issue, you can always revert.