If you have followed along every workaround and it still doesn't, look at this thread
They have an indicator that will output all the custom and final bars that have been already used. I had to switch the Custom4 to Custom0 because that was available. However, the Custom4 was already been used by another Bar type that I had installed.
This is what my output window looks like after changing Custom4 to Custom1 in BetterRenko.cs. Anything that has Minute after the first word are all available and can be used.