I have exactly the same problem with the RTD error. I have been using the IG API for many years, and the problem has cropped up from time to time.
Last time I think downloading a fresh copy of the Excel sample file from IG, and then cut and pasting all my extra code in seemed to work, but it does not seem so in this case.
As noted, the support for the API is terrible; I may also have to look elsewhere for a better system.