Thanks to Janis Plume from EasyBI Support for the solution
There is a limitation of the Matches function in eazyBI; this function is unable to work with multi-line text properties. The workaround is to replace the line breaks with empty string before applying the pattern matching.
CoalesceEmpty(
Replace([Measures].[Issue Checklist Text],
CHR(10),
""),"") MATCHES '.*open.*Security.*'
Example to extract status from Chechlist textfield
CASE
WHEN IsEmpty([Measures].[Issue Checklist Text])
Then ''
WHEN CoalesceEmpty(
Replace([Measures].[Issue Checklist Text],
CHR(10),
""),"") MATCHES '.*open.*Architecture.*' THEN 'open'
WHEN CoalesceEmpty(
Replace([Measures].[Issue Checklist Text],
CHR(10),
""),"") MATCHES '.*progress.*Architecture.*' THEN 'in progress'
WHEN CoalesceEmpty(
Replace([Measures].[Issue Checklist Text],
CHR(10),
""),"") MATCHES '.*done.*Architecture.*' THEN 'done'
ELSE 'invalid status'
END