For the past few 6.8 releases...
Steps to replicate
While in a new unsaved post, select attach existing files, select one or more files and then click "with selected files" does not display insert img/link option in the pop-up menu.
Work around: If you save the post first and then try to attach an existing file, select one or more files, the img/link option now appears.
Possible solution: I think in past versions, it prompted you to save the post first before you could attach a file.
@blex if you need to insert the image then save the post first.
I agree the above is less intuitive. However, maybe this wouldn't be considered as a bug but as a feature request.
I already sent it to the developers, so we will come to a decision about to how to deal with this and when to release it soon.
Regards!