Due to a limitation of Jira Cloud, which passes the post-function configuration in a GET URL that is limited to 8000 characters in total, JMWE cannot support long post-function configurations. The most affected are post-functions with more functionalities such as the Create/Clone issue post-function and the Transition post-functions.
Workaround
The easiest way to reduce the post-function configuration length is to replace the Nunjucks templates in the post-function with a Shared Nunjucks template. For example, you have a Transition issue post-function with a lengthy template to calculate the transition to be triggered:
Calculate transitions:
{% if issue.fields.customfield_12332 == "A" and issue.fields.customfield_11312 == "a" %}
"To Department A"
{% elif issue.fields.customfield_12332 == "B" and issue.fields.customfield_11312 == "b" %}
"To Department B"
.....
....