In your concatenated FD_FC_name attribute, is there a forward slash in between? If I want the Feature type (Feature Class) name to be dynamic I would rather have the dataset and the feature class in separate attributes with a forward slash in between.

Lots of nuances on writing to a feature dataset. Are you creating new feature dataset (s) and new feature class (es) in your translation?

What is the Feature Dataset Handling parameter on your feature type? 

Here’s the doc to check out which parameter to use:

https://docs.safe.com/fme/html/FME-Form-Documentation/FME-ReadersWriters/geodatabase/feature_dataset.htm

In your concatenated FD_FC_name attribute, is there a forward slash in between?

Yes there is a forward slash betweeen the Feature Dataset Value and the Featureclass value.
Also i tried it like the following picture:
 

Are you creating new feature dataset (s) and new feature class (es) in your translation?

No i use an exisiting Feature Dataset and an FeatureClass.

 

I am so confused, why the Table Handling Options “Drop and Create” is not doing what it is intended to do.
Instead all the features get inserted.

That is my Feature Dataset Handling parameter: 

When i set this to Off - Slahes becomes underscores FME writes it to the root of the EGDB and not into the Feature Dataset.




 

Is your sde connection file configured with the schema owner? Any error messages in the log?

The sde connection is configured with the schema owner.

I get the log messages in debug level: Specially the first long one seems to be the Problem, its not appearing when i use a static hardcoded string for the feature dataset.

class StatusInfo __cdecl STFGenericizer::processMetafile(const class stk::ex::UString<0> &,const class stk::ex::UStringArray<0> *,const class stk::ex::UString<0> &,const class stk::ex::UString<0> &,const class stk::ex::UString<0> &,const class stk::ex::UString<0> &,class STFAttributeName &,class STFMetaMapper &,class STFObjectNameConstraints &,bool &,bool &,bool &,class stk::ex::UStringArray<0> &,class stk::ex::UString<0> &,class std::vector<class STFFeatureType,class std::allocator<class STFFeatureType> > &,class stk::ex::UStringArray<0> &,class stk::ex::UStringArray<0> &,class stk::ex::UString<0> &,class std::vector<struct std::pair<class STFAttributeName,class stk::ex::UString<0> >,class std::allocator<struct std::pair<class STFAttributeName,class stk::ex::UString<0> > > > &,class stk::ex::UStringArray<0> &,class std::vector<class STFAttributeName,class std::allocator<class STFAttributeName> > &,class stk::ex::UStringArray<0> &,class stk::ex::UStringArray<0> &,bool &,bool &,class stk::ex::UString<0> &,class stk::ex::UStringArray<0> &,class STFObjectNameConstraints &,class stk::ex::UString<0> &,class stk::ex::UStringArray<0> &,class stk::ex::UStringArray<0> &,class stk::ex::UString<0> &)

class StatusInfo __cdecl STFGenericizer::loadMetaMapper(const class stk::ex::UString<0> &,const class stk::ex::UString<0> &,const class stk::ex::UStringArray<0> *,const class stk::ex::UStringArray<0> *,bool)

class StatusInfo __cdecl STFGenericizer::getFeatureTypeConstraints(const class stk::ex::UString<0> &,class STFObjectNameConstraints &)

BADNEWS: No MULTI_WRITER dataset name was specified (couldn't find a value for `FeatureWriter_3_DATASET' or `MULTI_WRITER_DATASET')

class StatusInfo __cdecl STFWriterImp::getDataset(class stk::ex::UString<0> &) const
 

If you can, please share your log file.

If that’s not possible, it would be better to reach out to Safe support. If you use ESRI’s ArcGIS Data Interoperability, guessing from your FME Engine number, you can reach out to ESRI support. 

Okay, thank you so much for your help.

I will try to reach out to the ESRI or FME support.