Had some problems the other day to get a form filter to execute. Found out that workflow task forms uses an own filterRegistry. So the spring bean definition have to be like this for example:
<bean id="myTaskFormFilter" class="se.redpill.alfresco.repo.form.filter.MyTaskFormFilter" parent="baseFormFilter">
<property name="filterRegistry" ref="taskFilterRegistry" />
</bean>
To create or remove a filter in one of the filter sections simply override the filter’s config file AND the task or workflow lists’ config files in the web-extension folder and add or remove a filter element. Make sure to match the filter