Pool floor issue new pool

[Gordon123]

After new 15x26 ft oval pool install i noticed a 5 inch circle about 2 inches deep in floor of pool where sand seems to have washed away. We did have pooring rain right after the install when the pool only had about a foot of water in it. Over the past few days I have noticed that the same dip in the floor liner has occurred inside the pool adjacent to each side upright of the pool.

Pool store said it will be fine but that at the end of the season they would like to come back, take down the liner and fill those areas up with sand again. I am concerned abotu draining the pool because one side of it is set in the ground a foot and half..

Will these unsupported areas of pool floor cause leaks? Should I be concerned? Will the pool be damaged if I drain it? I'm about to spend a lot of money on landscaping and dont want to if ill be digging up the pool again in the fall.