Each time I try to APPLY a PTF to my CSI I get the following message:
Product (CA Common Services for z/OS - MVS) Release (15.0) cannot be processed because the product/release is locked by an active task(s). Try again later. List of active tasks: 
What do I need to do to resolve?
If you select a CSI being used in MSM by another user or if there is a task currently running that has your CSI locked then you are prevented from performing any actions on the CSI until the user closes the Wizard that is accessing your CSI or the task that is running against has ended.
The alternative to waiting is to recycle the MSMTC which will end the TASK or Session Wizard that has your CSI locked.
Then start your MSMTC again and you will be able to select the CSI because the LOCK has been freed.