I remember your first thread on this issue.
If I had to guess by that picture, I'd say that looks normal. I don't own that particular IOR, so I can't say with 100% certainty. I have the M2.
The very edge of the scope body, where it is rubberized ( you can see the texture)...that part should spin. That is the "diopter" or AKA eye piece focus. Try spinning it. Don't baby it. Sometimes they are really stiff when new and take a little effort to rotate. I consider that a positive, because once focused, you don't need to worry about it being nudged to a different setting.
Don't be so concerned with the threading. Most scopes on the objective lense have a lot of threads on the inside of the tube, this is normal. You see the part where the rubberized diopter adjustment ring is? That is part of a tube that is the very same tube as those threads. The ocular lense (the one in the pic) is fitted in a ring, and that ring is threaded in (often times) and there is a lock ring on the inside. This is how the factory secures the lense. Why is it threaded? They can adjust the depth of the lense at the factory so that for someone with 20/20 vision, a diopter setting of "0" will appear clear and crisp. When you spin that adjustment ring, it basically moves the lense outward or inward, thus changing the focus.
I might be a little off in how this all works, but that is the general idea.
Also, you wouldn't want a scope having a lense all the way at the rear. It is a positive thing to have a "shaded" lense. Most optics, even the high end stuff with excellent coatings, suffer from bad glare when direct sunlight hits them. On an objective lense, this causes light artifacts in your view. On an ocular lense it makes it difficult to see through the scope at all.
I honestly don't understand why you think there is a missing lense. Is it because the scope is terribly out of focus for you??? Consider this, if a lense were missing, like the outer-most occular lense...you'd definately know it. The scope would be totally useless and you wouldn't be able to see through it.
IOR scopes have a WIDE range of eye-piece focus (diopter) compared to domestic scopes. My GF has absolutely horrible vision. Her prescription is so strong, it is worse than looking through a Coke bottle for me. With her naked eye, there is NO setting on most domestic scopes that allow her to see clearly. On the IOR, there is. This is most likely because IOR is really a company that's been building military-grade optics for a long, long time. They need to work for any soldier that might use it. She can focus it so she can use it without her glasses. If you're looking through it, and it seems very blurry...it is probably set to one of the extremes. Try and get that ring rotating, then adjust it, and I am sure it will look very crisp and clear.
If it already looks crisp and clear now, then you know 100% you don't have a missing lense because the scope wouldn't be usable.
***Edited to add...
I've never seen the power-ring on that IOR before...but judging by the picture on IOR's website, it looks like it has a seperate power ring that adjusts magnification independently of moving any other part of the scope -- check to see IF NOT..... then it is like the Burris scopes...the entire occular bell end of the scope rotates to change power...but the focus ring (diopter) rotates only on the very, very edge of that entire apparatus that rotates to adjust magnification. This can be annoying. It is a European thing, and as I understand it, Zeiss scopes are like this. So you might be rotating the power ring and just thinking that there is no way to adjust the diopter. If you looked at my burris, the entire rear rotates and if you didn't know that the rubber ring at the edge rotates independently..you'd never find it. Adjusting magnification doesn't screw up your focus (once set), but adjusting the focus will most likely move the magnification around...unless you hold the body of the bell with one hand, while turning just the rubber ring on the edge to adjust focus...that will prevent magnification change..but that's not a big deal.