error in Parallel Replica Dynamics simulation of sheared system

Dear developers and users,
I’m having some problems with Parallel replica dynamics simulations. I’m currently trying to apply the prd method in a system subjected to shear deformation at constant strain rate (using the erate style in the fix deform command). The problem I’m experiencing is related to the fact that the shear strain increases in an unexpected way (in particular more than what is specified in the fix deform command) in in the integration step immediately following the check for an event in the prd routine. After this anomalous behavior, which involve only one step and not depend on the fact that an event is found or not, the shear deformation goes on regularly according to the desired shear rate up to the next check where the error comes back. Moreover the magnitude of this error increases as the simulation goes on.
I thought it could be related to the preceding store_state and the following restore_state operations, but it does not seem the case
Any idea about the source of this error?

Thanks in advance