R extension "blocking" GIS extension

When I change something in my code related to the R extension (including adding R-commands within BehaviorSpace), this leads to NetLogo telling me that it can't find the GIS extension any more. I have to close NetLogo and open it again - then it works until I change something in the code. I use: 
Windows 10
NetLogo 6.0.4 (64 bit)
R 3.5.1 (64 bit)