REGRESSION - Relative date filters are not saved for new smart groups created in 4.7.X

I have smart groups with relative date filters created in v4.4.X. On a site that has been upgraded to 4.7 these work as expected. From the saved_search table I can see:

"contribution_date_relative";s:11:"ending.week";s:21:"contribution_date_low";s:14:"20160122000000";s:22:"contribution_date_high";s:14:"20160128235959";

However, if I create a new smart group using relative date filters on 4.7.10 the search criteria is saved as a fixed date range. Eg. for "last seven days including today" saved on 20 August 2016, in the saved_search table there is no reference to "contribution_date_relative" all I can find is:
"contribution_date_low";i:1;s:1:"=";i:2;s:14:"20160814000000"..."contribution_date_high";i:1;s:1:"=";i:2;s:14:"20160820235959";
and the "smart" group always returns results from 14 August 2016 to 20 August 2016 no matter what day it is used.

This is obviously a major loss of functionality.