In 4855 the oik shortcode buttons don’t work for the Classic block.
With oik 3.2.5 the shortcode buttons may not work at all, unless the theme or another plugin enqueues thickbox jQuery and CSS using add_thickbox.
Once that’s fixed the actual insertion of the shortcode appears to be random. The behaviour is a similar problem to #10509, which is related to the Add media button, a core component.
The fix to oik issue #100 has also resolved the problem of the buttons not working at all on my iPad.