When an Image gets added as an additional setting and is set, the delete-button does show up but can’t be clicked. Changing .contentblocks-field-actions z-index does solve the problem. Was able to replicate this on multiple installations, versions prior to 1.8.9 do not seem to have this problem. Anyone can confirm?
Yeah, received 2 other reports about this via email@example.com and will be looking at a fix shortly, hopefully before the end of the week.
Just to report back, this was fixed in v1.8.10.