scorecardpy.woebin - special_values error

[Maciej012AI]

I'd like to add "special_values" for function woebin in module scorecardpy on my data but it doesn't work. I try to use it with code from ShichenXie /scorecardpy :
import scorecardpy as sc
dat = sc.germancredit()
dt_s = sc.var_filter(dat, y="creditability")
train, test = sc.split_df(dt_s, 'creditability').values()
bins = sc.woebin(dt_s, y="creditability")
special_values = {
'credit.amount': [2600, 9960, "6850%,%missing"],
'purpose': ["education", "others%,%missing"]
}
breaks_adj = {
'age.in.years': [26, 35, 40],
'other.debtors.or.guarantors': ["none", "co-applicant%,%guarantor"]
}
bins_adj = sc.woebin(dt_s, y="creditability", breaks_list=breaks_adj,special_values=special_values)

There appears an error:
ValueError: cannot convert float NaN to integer

Or when I change special_values on
special_values = {
'purpose': ["education", "others%,%missing"]
}
There appears an error:
MergeError: Can only pass argument "on" OR "left_index" and "right_index", not a combination of both.

Could You help me ? Do You have any idea why it doesn't work ? Without "special_values" it's ok.