Managesieve using Regular expression with ignore case flag

[dkrasko]

I have a filter setup in my RoundCube email box that if a message body does not contain the word "meeting" to move it to my "other" folder.
I've tested my regular expression using an online tool and it works  ignoring case. My expression is:

\b(meeting)\b/i

I've defined the filter (see attachment)
as matching any of the following rules, body - not matches regular expression - \b(meeting)\b/i

The ignore case flag in my regular expression does not seem to be recognized by sieve filter.
How do I set ignore case in my RoudCube sieve filter?