The cursor mentioned in the warning message is a relative value used in the rule_Log API call (https://api.asm.ca.com/1.6/rule_log?doc) to retrieve large sets of sequential monitor results. The cursor value allows these results to be retrieved in chunks. For example, 200 logs result can be returned in sets of 50, if the same rule_Log API call is made using the cursor value return in the previous invocation.
The warning message occurs when this cursor value becomes invalidated. The APM agent then fails to retrieve ASM data on subsequent rule_logs and only partial sets of ASM data are returned.