lmerTest in R versus lme in statsmodels/Python

Question

I do have a complex linear mixed effect model.

model_lme = MixedLM.from_formula("Ratings ~ LCDev455*ST0LT1*TargetType*Female0Male1", groups=data["ResponseID"], data=data)
model_lme = model_lme.fit()
model_lme.summary()

This perfectly works in R, lmerTest. Not even a convergence warning. But in python statsmodels, it gives the error: Singular matrix.

I thought that these two packages (lmerTest in R, lme in Python) were giving the same output.

Does anyone have any idea why this might happen? I am more of a beginner so I cannot really simulate my data here.

Thank you!