have only just seen this post. Sorry for a late response.
Accessability changes, hedgehogs die, get eaten, run over etc.
Dogs nearby, lights on, good natural foraging could all be factors.
They travel a mile or so at night, so can have big territories.
Your supplementation might not have been needed for some time; this time of year, maybe, more supplement (and water of course) could be required.
Don’t give up. have you spoken to any neighbours about sightings/access?
i have 3 feeding stations which are not used every night but also have 3 hibernacula, all used for the first time last winter.
One hog. on the small site that I live on has already bagged a hibernacula!
Please keep the faith and help as much as poss. Numbers keep going down and “yours” could have been one of them. let’s hope not.