(just an update on my troubleshooting here)
It looks like the version of PHP that comes installed with the version
of Ubuntu that Observium recommends is limited to 32-bit signed
integers:
root@xxx:/opt/observium/includes/polling/applications# php -r 'echo
PHP_INT_MAX;'
2147483647
That explains the issue that I have been having with bind counters
above this value being saved at a value of 2147483647.