wflow.finalize() not working (2020.1.2)

wflow.finalize() results in an error for version 2020.1.2:

`_InactiveRpcError: <_InactiveRpcError of RPC that terminated with:
status = StatusCode.UNKNOWN
details = "Exception calling application: Data source /gpfs/work1/0/wtrcycle/users/jaerts/rogier_output/wflow_20220118_092800/run_default/outsum/RiverWidth.map(raster):
cannot be created"
debug_error_string = "{"created":"@1642498157.812507164","description":"Error received from peer ipv6:[::1]:56907","file":"src/core/lib/surface/call.cc","file_line":1063,"grpc_message":"Exception calling application: Data source /gpfs/work1/0/wtrcycle/users/jaerts/rogier_output/wflow_20220118_092800/run_default/outsum/RiverWidth.map(raster):\ncannot be created","grpc_status":2}"`

It seems that there is no permission to create the "outsum" folder. Creating the outsum (and "outstate") folder manually before finalizing the model results in creation of files in these folders. However, the following error occurs:

`_InactiveRpcError: <_InactiveRpcError of RPC that terminated with:
status = StatusCode.UNKNOWN
details = "Exception calling application: 'NoneType' object has no attribute 'sync'"
debug_error_string = "{"created":"@1642498284.163238042","description":"Error received from peer ipv6:[::1]:56907","file":"src/core/lib/surface/call.cc","file_line":1063,"grpc_message":"Exception calling application: 'NoneType' object has no attribute 'sync'","grpc_status":2}"`

Last lines of the wflow.log:

`2022-01-18 10:29:17,812 - wflow_ewatercycle.ini - wf_DynamicFramework - INFO - Saving summary maps to disk...
2022-01-18 10:31:24,111 - wflow_ewatercycle.ini - wflow_sbm - INFO - Saving initial conditions...
2022-01-18 10:31:24,131 - wflow_ewatercycle.ini - wf_DynamicFramework - INFO - Saving summary maps to disk...
2022-01-18 10:31:24,163 - wflow_ewatercycle.ini - wf_netcdfio - WARNING - Finishing before expected run-length exceeded. Buffer not flushed`