I have situation when my projects are not always visible to phpStrom when it is opened.
1. When my project are at Truecrypt volume which was not mounted yet as drive.
2. When my project are at network share which is not mounted yet as drive.
If I run phpStorm and the mounted project location are not there the "Reopen Recent Project" entries are cleaned (!).
So I must add all projects again.
I'd suggest to remove that functionality because there is a menu position "Clear the list". Or better to add individual clear button for each project entry.