I think it's because you added a space between the text/picture for #3 and so Steem considered the Number reset. It is confused and thinks you wrote another list. The actual number you type in doesn't matter, Steem will just consider it part of a list.

For example:

1. Here's one thing
2. Here's another

Something in between

1. It starts over even though I put 3

One way to fix this is to not put the space between the text and picture:

1. Here's one thing

2. Here's another
   Something in between

3. It doesn't start over again

Hope this helps!

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