When we are in Template Mode, if we select a timeframe already used in a Non Template mode, we have an error and we can not save it.
We have to turn off the template mode, select another TimeFrame in a non template mode (different from the template mode) , then turn on the template mode.
Please see the attached video.
Subject changed from [Build 137.1639 RC3] In Template Mode, SubChart TimeFrame Selection with error to AW [Build 137.1639 RC3] In Template Mode, SubChart TimeFrame Selection with error