Well, a seam will do this over time, and I would think 10 years in a place like a kitchen is a long time.
What has happened, is that water, dirt, debris, grease and stuff has worked its way in the crease and then under the crease causing the cement or mastic to work loose.
I am sorry, but this is the drawback with a seam.
Others may have a remedy, but they are all bandaids I would speculate.
I would consider a new flooring and one that the seam is better situated or with out.
Sorry about that.
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