Whenever I write a comparison using the scripted JQL function expression(), e.g.
issueFunction in expression("", "customfield_XXXXX > customfield_YYYYY")
if the custom fields are numeric, I get an error on the issue navigator. Happens if I try "customfield_XXXXX > Y", as well, even when that works in ordinary JQL.
Here's what's printed in the jira log:
("'00000000000099.000' é um número inválido" translates to "is an invalid number")
If the fields are dates, they work as expected.