Very slight movement in tiles around shower tray. - Tile Advice

[simbaali]

Hello,

So I have a small shower tray that has 4 upstands and the tiles placed on top. The gap between the shower tray and top of the tile is about 1cm.

I've noticed at the bottom tile that if I push it I see slight movement. My worry is that water is getting behind and slowly working its way up the wall but I don't see how? No leaking on the tiles outside the tray and no leaking under the vinyl.

When tiles are put on top of the tray can there be movement at the bottom as I'm assuming there isn't plasterboard to support it at the very edge? Any idea how to know without ripping the tiles off?

 

[Slippery]

Are you saying that the bottom tile is only 1 cm high?

I think we need pictures to understand this.

 

[pete f]

I'm not too sure about the description but when this happens it's normally the substrate that's damaged behind the tiles