Ultimaker 4.2.1 won´t print a certain .stl anymore

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Hi, 
I updated to Ultimaker 4.2.1 and now a model that I created in 2018 and I am printing every few weeks isn´t printing anymore. 
When slicing, it just prints a Tower and useless support structures : 

-> this is the model x2 before preparation : 

 

and this is the simulated print : 

 

-> the Model is completely ignored and there are just useless support structures printed 

 

what could be the reason ?! 

 

I exported it again as .stl from the model, but nothing changes this situation.

I can print every other model without problem, but it´s just this specific model since Update to 4.2.1 .... 

 

Could it be a Bug in the 4.2.1 - Version ? 

 

It´s definitely not the model, it has been printed a thousand times before flawless..... 

 

04_RadsensorPanel_Raw_trianguliert_V4_final.stl