Datapump export to ACFS with UEK6

anybody having 19c databases with a data_pump_dir on ACFS using UEK6? Can you successfully do a datapump export?

With UEK6 (5.4.17-2136.301.1.3.el7uek, and also older versions of UEK6) I get the following output in my datapump logfile:

Export: Release 19.0.0.0.0 - Production on Wed Dec 1 19:31:51 2021 Version 19.13.0.0.0

Copyright (c) 1982, 2019, Oracle and/or its affiliates. All rights reserved. ;;;
Connected to: Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production

ORA-39097: Data Pump job encountered unexpected error -31644
ORA-39065: unexpected master process exception in FILE
ORA-31644: unable to position to block number 2 in dump file "/u02/datapump/expdp_acfstest.dmp"
ORA-06512: at "SYS.KUPF$FILE", line 4430
ORA-06512: at "SYS.KUPF$FILE", line 2676
ORA-19502: write error on file "/u02/datapump/expdp_acfstest.dmp", block number 1 (block size=4096)
ORA-27061: waiting for async I/Os failed
Linux-x86_64 Error: 22: Invalid argument

ORA-06512: at "SYS.KUPF$FILE_INT", line 80
ORA-06512: at "SYS.KUPF$FILE", line 2573
ORA-06512: at "SYS.KUPF$FILE", line 4410


Expdp parameter file is quite simple:
DIRECTORY=DATA_PUMP_DIR      <- DATA_PUMP_DIR is on ACFS

SCHEMAS=MYSCHEMA
EXCLUDE=STATISTICS
CLUSTER=no

MYSCHEMA.TABLE2:"WHERE 1=2",
MYSCHEMA.TAB3:"WHERE 1=2",
MYSCHEMA.TAB4:"WHERE 1=2",
MYSCHEMA.TAB5:"WHERE 1=2",
MYSCHEMA.TAB6:"WHERE 1=2"

When I boot the VM with UEK5 (4.14.35-2047.508.3.2.el7uek and also older versions of UEK5 ) the same datapump export works without problems.

Some futher information about my environment:

OS: Oracle Linux 7.9 x86_64

Grid Infrastructure is on 19.13:
$ opatch lspatches

33239955;TOMCAT RELEASE UPDATE 19.0.0.0.0 (33239955)
33208123;OCW RELEASE UPDATE 19.13.0.0.0 (33208123)
33208107;ACFS RELEASE UPDATE 19.13.0.0.0 (33208107)
33192793;Database Release Update : 19.13.0.0.211019 (33192793)
32585572;DBWLM RELEASE UPDATE 19.0.0.0.0 (32585572)

Database also on 19.13:
$ opatch lspatches

30978304;ORA-20000 DURING IMPDP WITH STATS AND THE UNIQUE INDEX FOR THE PK IS NOT CREATED
33208123;OCW RELEASE UPDATE 19.13.0.0.0 (33208123)
33192793;Database Release Update : 19.13.0.0.211019 (33192793)

Maybe anybody has the same issue?