I have a couple of question about this problem:
a) What device family does the device belong to? Cisco IOS which is default
b) Are the capture of others devices from this same device family okay? Only happen to certain CISCO device. Other CISCO device is success.
c) Is there any overriding of the Local Communication Configuration on the device? No
d) Verify if the TFTP Directory has any lingering transfer file. No
e) A WireShark capture while attempting a capture need to be reviewed. Not tested yet
f) Have you tried saving the Cisco configuration using SNMP manually?. Not tested yet