Libdl.find_library does not find library in current directory

For some reason Julia 1.1.0 can no longer find my shared library (written in C, compiled with MinGW gcc) on Windows 10 (64-bit).
The commands I use are

run(`ls mylib.dll`) # is the lib in my current folder?
    #outputs: mylib.dll
    #outputs: Process(`ls mylib.dll`, ProcessExited(0))
using Libdl
find_library("mylib.dll", [pwd()])
    #outputs: ""

By the last output, Julia can’t find the library even though it is in the working directory.

This worked before but stopped after a crash while using Atom where I had to reinstall the julia-client package. I do not know if that is related

I tried to reinstall Julia, but nothing has changed.

What other steps could I take to debug why is my library not being found?

What happens if you do:

dlopen(joinpath(pwd(), "mylib.dll"))

(since this is what find_library does internally to check whether the library exists in the path you specify)?

It gives an ERROR: could not load library

 [1] #dlopen#3(::Bool, ::Function, ::String, ::UInt32) at C:\cygwin\home\Administrator\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.1\Libdl\src\Libdl.jl:109
 [2] dlopen at C:\cygwin\home\Administrator\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.1\Libdl\src\Libdl.jl:109 [inlined] (repeats 2 times)
 [3] top-level scope at none:0

I do not understand why the pathing to cygwin. I installed Julia using the julia-1.1.0-win64.exe file, without touching cygwin (which is in a folder named cygwin64).