I have TB 69 b4. For some reason I no longer have the insert => image command when I go to write a message. It may have disappeared earlier - it’s been a little while since I sent a message with an inline image.
I’m on TB 69.0b4, can confirm that both the menu option “Insert > Image…” and the toolbar option (screenshot below) are there:
Just wondering - do you have the composition in HTML option enabled? Insert image is a rich formatting option which wouldn’t be available if you’re composing the message in plain-text.