Here's the FAR reference:
Ref FAR 65.155(d) "An applicant who successfully completes the knowledge test for an airline transport pilot certificate prior to August 1, 2014, must successfully complete the practical test within 24 months from the month in which the knowledge test was successfully completed. An applicant who passes the knowledge test prior to August 1, 2014, but fails to successfully complete the practical test within 24 months must complete the airline transport pilot certification training program specified in §61.156 and retake the knowledge test prior to applying for the practical test."
Yes, it looks like the FAA, as usual, is making rules for the airlines without a thought to the others.
GF