Ropper: Getting '[ERROR] list index out of range' when trying to load file

Running Ropper on Windows, with capstone-windows 3.0.4, then entering the command file C:\Users\MyUser\test.exe results in the output:

[INFO] Load gadgets from cache
[LOAD] loading... 0%[ERROR] list index out of range

Then entering the command search "% ?di" results in the output: [INFO] Searching for gadgets: “% ?di” [ERROR] object of type ‘NoneType’ has no len() [ERROR] Please report this error on https://github.com/sashs/ropper

Additionally, running the command ropper.py --file C:\Users\MyUser\test.exe -- search "% ?di" results in a continuous loop of this error: [INFO] Load gadgets from cache [LOAD] loading… 0%[ERROR] list index out of range [ERROR] Please report this error on https://github.com/sashs/ropper

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\Users\MyUser\Python\lib\multiprocessing\forking.py", line 347, in main
    self = load(from_parent)
  File "C:\Users\MyUser\Python\lib\pickle.py", line 1378, in load
    return Unpickler(file).load()
  File "C:\Users\MyUser\Python\lib\pickle.py", line 858, in load
    dispatch[key](self)
  File "C:\Users\MyUser\Python\lib\pickle.py", line 880, in load_eof
    raise EOFError
EOFError