xtedx

yes, same here with wp4.5.3 and cf 4.4.2 and datepicker 2.5.2 it seems that the plugin is no longer maintained from the github page https://github.com/relu/contact-form-7-datepicker/

we need to find another way

i found out that avada theme is overriding the .wpcf7-select class
giving z-index: 5, while the datepicker has z-index: 1
therefore causing the datepicker to be covered.
after i fixed the css, it seems to be working fine.
now both of them have z-index:1