I'm not sure what the changes were, however I am posting to say I am not experiencing this on my organisation's Promapp instance.

We have similar reference numbers as you for some processes (i.e. 4.2.3.1, etc), and searching by this reference number only without quotations works, the process comes up at the top of the dropdown as expected. 

Is it possible there are spaces/other blank characters in the reference that might be affecting the search? 

Hi I appreciate your quick reply and comments.

In the case I have here the process is unpublished. We do seem to have OK search on published processes.

This Help site describes "Current Search" and "Advanced Preview Search".

https://help.nintex.com/en-US/promapp/IndexedSearch.htm

As I am not offered the "Include Unpublished Content" option, this would suggest we are using the "Advanced Preview Search" (but I'm not sure where this control is driven from).

he documentation says that unpublished items should be included in search results but it does not seem to be the case for us.

Can you do searches in a similar way on unpublished processes? Cheers

I have checked with unpublished processes now, and yes, the reference search doesn't work for these, the same as you have described. 

I'm not sure on the solution for that - we wouldn't expect users to be searching for unpublished processes given they won't be able to access them 99% of the time anyway.