In T128733#7184816, @Kghbln wrote:

@Joris I had this too just last week. Just remove the list parameter form the field definition to move on. In this case you can use separators again.

The issue reappears in this combination:
{{{field|test|list|values from namespace=File}}}
Example: https://sandbox.semantic-mediawiki.org/wiki/Formulaire:T128733

Perhaps @Vid would elaborate on his work-around? The very minimum would probably be documenting this behaviour.
Though - without having delved into the architecture of Page Forms - I hope we could create a parser function that directly creates the desired edit-with-form tab (forgoing any intelligence that would require jobs to be run).

@Yaron_Koren ah sorry, I missed it indeed! One of the example pages is https://sandbox.semantic-mediawiki.org/wiki/Issue/Default_form/Test2018-05-30. But as that page is more than a few minutes old, you can see the tab now. The issue is, it didn't show the tab the first few minutes after saving the page.
Older tests were https://sandbox.semantic-mediawiki.org/wiki/Issue/Default_form/Scenario_1 etc.

Just to be sure: @Yaron_Koren you seem to be still hinting at templates causing the delay, but if I create a page with {{#default_form:Article}} in the contents of the page itself, the edit with form doesn't show up.
I replicated this on the public SMW sandbox (MW 1.31.0-rc.0, Page Forms 4.3.1 (a3c23fe)) and on a wiki running MW 1.27.4, Page Forms 4.2.
@Vid could you expand on your issues with saving pages with templates? And could you check if {{#default_form}} works instantaneous if you add it to a page directly?

Thanks for your reply! That is indeed true for the tested wiki's; they were also upgraded to new versions of MW and SMW.