Only during early 2015 when express entry was first launched. Probably due to lack of clarify for officers with new system or it was a part of requirement then. No one after that. Not everyone follows this forum to know this and upload TRF along with educational certificate.Other applicants in the past have also reported that their applications were cancelled for being incomplete because they didn't include their IELTS certificate.
this is the mandatory list of documents specified by CIC. TRF is not a part of it.
http://www.cic.gc.ca/english/resources/tools/perm/express/intake-complete.asp
One possibility is OP's CSE/response did not reach properly after they requested TRF and they might have cancelled due to that. It will be clear if he posts the letter.