There have mixed issues. NAT 1.3.673 and 1.3.681 are buggy but you also are modifying NAT session in a way that template are not ready for deconvolve.
NOTE: in NAT3, NAT3 FREE, etc. Templates are embedded in NAT sessions. You can not change anything in sessions for change templates and if you create a session with a wrong parameters NAT will stop or crash during deconvolution.
To make thing more clear NAT session = sampling NAT template = deconvolution
NAT session can be modified in a quite open way but if you add dimension in a session with a template that is not ready for that, NAT will stop or crash during deconvolution.
do not change templates. Use sessions as is. The only thing you could do is trying deconvolve later using a different and similar template. Im not sure about switch, it should be 'snappy'. Just check if what I remember is correct.