In current beta-version of WebUntis Substituion Planning at the moment there is following limitation:
Before WebUntis Substitution Planning Beta gets activated, the school administrator should ensure, that time zone is set correctly in WebUntis:
1) Administration > 2) Settings > 3) Time zone
In case there is no time zone configured before activation, then WebUntis Substitution Planning will show wrong time.
Even if time zone is set afterwards, wrong display will only be correct, after a reset of the data base of substitution planning.
So better to set it correctly before.