Actxserver no longer working correctly in R2018a, is there anything I can do to fix?

I have a custom (written by someone else) .dll for dealing with a complicated binary file format. I am currently using R2016b and it works fine. My colleague has installed R2018a and it no longer works in the same way, preventing him from reading any files.

The code is as follows: h_file = actxserver('Rp66COMLib.CSlbDLISFile'); %Rp66ComLib is my DLL h_file.invoke(filename);

when I look at h_file on R2016b it is a Com object that has Interface objects that make sense when I look at h_file on R2018a it is a Com object that has an Interface object that seems random (Interface.942CFC0B_8F61_4F6B_83C9_60C8CB185ED7)

[Guillaume]

It is very unlikely that the problem is from actxserver. Most of the work is delegated to the OS and the dll. In particular, which interface is returned has nothing to do with matlab.

[Steven Lord]

Define "no longer works in the same way."

Does it throw an error? If so, what is the full text (everything displayed in red) of the error messages your colleague receives?

Does it issue a warning? If so, what is the full text (everything in orange) of the warning messages?

Does it behave differently? If so, what is the nature of the difference in behavior? Different numbers in the results, different sized results, different typed results, etc.?

Does it do something else? If so, describe the behavior in more detail.

Are you using the exact same DLL in each MATLAB session?

Are you reading in the exact same file in each MATLAB session?

[Matthew Sullivan]

It is the exact same file and the exact same DLL. Both machines are running Windows 10.

The actxserver does not throw an error. I get an error later on when I try to read a structure from the object that is returned. The structure that I expect to be there is not. Instead I have an Interface.942CFC0B_8F61_4F6B_83C9_60C8CB185ED7 (or other random string of letters and numbers).

The first difference I notice is what I mentioned above. The object in R2016b has a reasonable name for h_file.Sets = Interface.Rp66COMLib_1.0_Type_Library.ISlbDLISSets

whereas in 2018a I get Interface.942CFC0B_8F61_4F6B_83C9_60C8CB185ED7.

It is possible that there is something wrong with the machine or with windows, I'm not sure how to rule that out.