Scheduled sends error: Query task xxxxx results not found in cache

[sergesever]

Scheduled send fails with the error:

‘Query task xxxx results not found in cache’ 

model-level max_cache_age is set to 24 hours, 
and schedule fails in < 1 hour

one idea is that it is  --scheduler-query-timeout=<i> being set to 1200 seconds by default
https://help.looker.com/hc/en-us/articles/4420218572819-Startup-flags-for-scheduling-Community- 

any help on how to manage timeouts on Looker-hosted environement?