I have had this happen a couple of times for three different applications.
I deploy an application to a Device Collection. It appears in Software Center just fine, install, uninstalls work as well.
Then at some point the "AVAILABLE AFTER" date displayed in Software Center changes to 4/10/1998. After that happens, it may or may not function any more.
I have tried deleting the deployment and setting it back up. Uninstalling and re-installing the Config Mgr client. Rebooting the servers.
Rebuilding the application within SCCM appears to be the only thing that fixes the date issue and brings the application back to life.
Any suggestions would be greatly appreciated?