Passport Canada has issued the following statement regarding X gender markers that clients should be aware of:

We can’t guarantee that other countries you visit or travel through will accept the sex or gender identifier on your passport or travel document. Check with our local Canadian embassy, high commission or consulate in the countries you plan to visit or travel through to make sure you understand their entry requirements.

You should also be aware that current systems used by some countries and travel companies may not recognize the X gender identifier and you may still be asked to provide your sex/gender information as either Male or Female when travelling.