Hello. Basically the "sep" parameter doesn't work with template format. For users wishing to use custom separators between templates, they may use {{#ask: [[Located in::Germany]] | template = formatting template name goes here | format = list | sep = <br>}}
(where the sep argument could be anything).
The example where I observed this behavior was on this page. (MW 1.23.2, SMW 2.0)
Relevant github report here.