The "[same as source file]" feature is temporarily no longer available in the later versions of Switch as there were issues with its implementation in the older versions which resulted in strange errors and caused many users problems, which is why it is temporarily unavailable in this release. It is only appearing there because you likely upgraded from an older version, and the settings were copied over. An exact path must now be specified to convert to. Here is what's written on the change log:
FIXED: some serious architectural bugs to do with selecting output folder as option [same as source folder]. For now it has been removed and will be added back in a next version.