Dear Jurgen,
I have edited my release strategy so that each characteristic has a threshold value, and afterwards tried to create a purchase order (tcode ME21) where the purchasing organisation, purchasing group as well as net order value fulfilled the criteria for triggering a release strategy. I also made sure that the PO time&date is preceded by the recent changes that I have done to my release strategy. Unfortunately, my new purchase order was still not subject to the release strategy.
I will now try to find a way to delete one of the unnecessary 'net order value' characteristics from class so that it is not included in the release strategy. I will also try to search for inconsistencies in my release strategy and purchase order in line with Bijay's advice above.
Thank you for your comments.
All the best,
Radoslaw