Not alerting if can't see it

We trained scentwork by using switchboxes and then little slide-top tins. We then tried to move on to novel objects or even the cotton bud itself but if my dog can't see it, he will find it, not alert, and then move on.

Do I just reward him as soon as he finds it but doesn't alert? My worry is I'd be rewarding a find with no alert and then breakdown all the work we've been putting into his indications. TIA!