Only in case the OBIEE was originally on another installation and was upgraded or ported from a different installation, where the same user existed, there are cases you don't see MyFolder.
To solve it you should alter instanceconfig.xml. (MWHOME\instances\instance1\config\OracleBIPresentationServicesComponent\coreapplication_obips1)
Check the line after <UpgradeAndExit>false</UpgradeAndExit>
If the tag <UpdateAccountGUIDs> does not exist add <UpdateAccountGUIDs>Recover</UpdateAccountGUIDs>
If it exists, change the value to Recover.
Restart the BI using EM or with the opmnctl command. The presentation Service can't start with the value Recover.
Return the instanceconfig.xml to its original state.
Start the Presentation Service.
You should see MyFolder in your next login.