If you crouch and right click a Strider to ride it, you will not move as expected, however, the Strider's health bar can be seen for a brief time (less than a second), and the Striders head snaps back like it would when you're riding it. When you do this multiple times, you will find you are unable to ride the Strider anymore until you crouch again. If you do this and walk away from the Strider and crouch, you will be teleported back to the place that you right clicked the Strider while crouching.
Thank you for your report!
We're actually already tracking this issue in MC-173404, so I resolved and linked this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature in the future to see if the issue has already been reported.
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