MatlabEngine %1 is not a valid win32 application

I am having a similar problem to the issue addressed in this question. I have two MATLAB installations on my Windows 7 computer, one 32-bit (2010b) and one 64-bit (2018b). I am trying to use the 2018b MatlabEngine in a Java program (using NetBeans 8.2, Java 8), but when I try to run "MatlabEngine eng = MatlabEngine.startMatlab();" I get the error "Exception in thread "main" java.lang.UnsatifiedLinkError: C:\MATLABr2018b\bin\win64\nativemvm.dll: %1 is not a valid win32 application".

I have removed the 2010b path from the Windows enviroment PATH variable, and checked that default command line "matlab" opens 2018b. I've tried reinstalling 2018b and renaming the 2010b application folder as well as the %APPDATA% folder to take any old files out of known paths. I keep getting the same error and am out of ideas.