Hi @Christophe,
It is a known and old bug in Orekit DSST propagation. We first encountered this bug in the Batch Least Squares orbit determination using DSST propagator.
After investigation, we found that this bug is link to the use of the DSST propagator inside a Propagator parallelizer in osculating mode. Meaning that the bug can be encountered outside without orbit determination.
An issue is already open for this bug (#717). I developed two tests to reproduce this bug: one in Orekit 9.2 (i.e. before the introduction of DSST OD) and one in Orekit 10.2 (i.e. after the introduction of DSST OD). However, I did not started working on fixing this issue. Contributions are welcome 
Best regards,
Bryan