If you are going to have to relay the tile, look into Schluter
trim and expansion joints for ceramic. Ditra, and others, make
crack isolators/spanners for concrete joints, but your problem
does not seem to be related to transferring a crack from below.
Are you sure there are adequate fasteners in the subfloor to
The typical treatment for expansion joints would be to leave out
the grout, but seal the joint with color matched urethane or
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