You can get around it by adding the following fields to the URL:I guess what struck me as particularly perverse here is that putting the year of baptism into the birth field always used to work, and when it ceased to do so, then I would put the date in the Any Event field instead, and pick Baptism from the dropdown. However, for the Oxfordshire register sets there is no date option in the Any Event field, so that scuppers that possibility.
&event=YYYY (where YYYY is the event year)
&event_x=R-0-0 (where R is the number of years on either side)
Note: when you use this trick R can take values that Ancestry wouldn't normally allow, such as 3.