Sentinel HASP Pro Problems with VS 2015 (CPP) and Envelope

We have previously successfully used the HASP Pro dongles to lock our software, as follows:
1. LDK - envelope-protect our EXE and DLLS
2. our software queries the dongle ID on start-up and compares with an encoded
3. for delivery to customers, we build an installer which runs haspdinst.
Our software was written and compiled using Visual Studio 2003.

We are now using Visual Studio 2015 and I am trying to lock our software to the dongles and I find that if I envelope protect the EXEs and DLLs as before, the software won't run when the dongle is plugged in. On some computers, it generates an error message ("xxx has stopped working Windows can check online for a solution to the problem") and on others it quietly terminates. Sometimes it hangs and you have to end the process from the task manager.

I have been using 5 computers, 1 of which is running windows 10 and the others Windows 7. The developer environment is installed on a windows 7 machine.

When we build our software, we link against the following libs:
legacy_stdio_definitions.lib
libhasp_cpp_windows_mtd_msc7.lib,
libhasp_windows_106576.lib

If I don't use Envelope, our licensing procedure works and the software runs, but we lose the extra level of protection.

Any ideas??