@TonyFleisher is correct…best to tag me or put these types of questions in the main thread.
As for your issue. I do this (mode changes) on a daily basis, so it does work. Please share your piston if you are using WebCore so we can troubleshoot this.
As for the timeout, per the instructions, they are present in my WebCore and look like this:
I just tested these and they do work.
Could this be a case where you added the switch DTH AFTER you added it to WebCore? If so, some of the custom commands are not populated to WebCore until you remove and then re-add the switch in the WebCore app.
Could the issue also be that the parameters are changing but not reflecting in your mobile app? That is not a DTH issue but a refresh issue on SmartThings’ side.
Let me know if that helps.