I have bought plants that had the wrong marker on them. Very disappointing. However, your peppers may turn yellow when the time comes. Leave them awhile. Even most green peppers turn red if left alone on the plant long enough.

Good luck with yours, let us know later if they did turn.
Bill P.

Yep, while are at least two cultivars of green ripe bell peppers out there, they are rare in the extreme. The typical green bell turns red, yellow or orange when ripe. Usually takes 20 -40 days beyond the green stage.

Just a thought that these pictures might help in some way to see the progression from green to yellow on the bell peppers.
From left to right, yellow to green.
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And some from green to red. Actually, the yellow bananna pepper at the bottom would turn red if left on the plant long enough, and most say that the fully ripe ones are the sweetest ones.
Bill P.
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In zone 8 you have plenty of time left for theose peppers to ripen. I've always thinned the peppers a little by picking a few of the full sized green fruits. The remaining peppers will ripen sooner. Keep in mind that you'll have less ripe peppers but usually more usable peppers, less spoiled ones.

Not sure which varieties you are growing but there are a number of varieties (Early Snsation, Zsa Zsa) that begin yellow and are fairly sweet as unripe peppers go. You might want to try just a few of those next year to complement your large yellow bells.

I'm not going to pick on Bill, but the yellow bell pictured would not be marketable for me. I mention this because it is common to have overripesides, sunscald , bug damage and especially rotting on peppers as they are left on the plant longer. I pick 90% of my bell peppers with some amount of green on the fruit and my customers accept that. There are even a few (one emailed me for a few bu. of 50%yellow just a few min. ago) that prefer some green to assure themselves that they will have firmer peppers for processing.

I do not market my peppers, just grow them for my own use and that ripest one was overlooked and did get too ripe. Of the other two, quite a bit of green is still showing and the third one is mostly green. I think that it may be still usable if I needed it, but have already thrown it into the compost. I posted those in hopes that to illustrate the progression of them changing color might help the original poster a little bit in some way.

Perhaps might come closer to meeting your standards. However, once again, these were grown in my home garden and basically organically, not intended for marketing.
Bill P.