Extending the end time of a timer created by autotimer works fine until autotimer runs again and changes it back.
One solution is to disable the autotimer in question, but you need to remember to re-enable it later.
Would it be possible in some way to prevent autotimer from changing the new end time?
Maybe change the timer type to a one-off timer? (This would probably result in another auto timer being created.)
Or flag the timer as "changed by user", so assume it's ok.