Grout Or Sealant

[Old Mod]

Is this on a wooden substrate or concrete

That's the former joint hey Andy!

 

[Old Mod]

It looks like there's movement on the former tray to floor transition by the screen.

If that was my shower floor it'd be screen out, and 5 tiles on that screen line and the cut tile to left would be straight out.
Inspect former and drainage for damage and if poss re tank and re tile.

 

[Andy Allen]

I've no idea unfortunately, is there 'no destructive' way i could find out?

Looks like movement to me or the wrong grout used....

 

[Old Mod]

Well if it's a recurring problem I'd go for movement. Drain not looking it's best and missing grout just in front.

 

[bcd-87]

All for movement say "I"

 

[Phil164]

The bit on the floor tray to floor transition was where I've raked out, but it was cracking there though.

 

[jobdone]

Looks like a Novallini shower former.
Its a foam tray with cement faces. Needs proper support underneath and on the transitions to the rest of the floor. Tray looks to be a 1200mm x 900mm where after that the grout looks sound. I would be with the others in saying it is movement.