Same Problem.
New Synthesis Version Cause this Error and Blocking Error Message.
Utilities\ExLoadOrderUtilities.cs(34,36): error CS1061: 'ILoadOrder<IModListing>' does not contain a definition for 'HasMod' and no accessible extension method 'HasMod' accepting a first argument of type 'ILoadOrder<IModListing>' could be found (are you missing a using directive or an assembly reference?)
Utilities\ExLoadOrderUtilities.cs(34,36): error CS1061: 'ILoadOrder<IModListing>' does not contain a definition for 'HasMod' and no accessible extension method 'HasMod' accepting a first argument of type 'ILoadOrder<IModListing>' could be found (are you missing a using directive or an assembly reference?)
Synthesis UI was just upgraded today and it looks like your patcher is using a deprecated function (see below).
Utilities\ExLoadOrderUtilities.cs(34,36): error CS1061: 'ILoadOrder<IModListing>' does not contain a definition for 'HasMod'