The customisation variable display-time-show-icons-maybe still exists in 1.17, but is ignored. The only references to that variable are in the defcustom declaration itself and in comments. Icons are always used regardless of this setting. Issue should be reported upstream, 1.17 should be masked. 1.14 works fine.
I have asked upstream about this issue: https://firstname.lastname@example.org/message/JNQZKQLYBHWCGDSMJHDKATNMLN6CPYS4/
The package has been updated by upstream. Waiting for the package to be released until taking further action.