Does anyone elese out there have any issues with Shimano SPDs feeling a little loose at certain points in the pedal stroke?

It’s a little hard to define, but I have brand new pedals and cleats and find that if I pull hard on the up-stroke, the cleat doesn’t feel totally locked into the pedal – there seems to be some vertical play (only around 1mm or so) and the pedal rocks up and down. Tightening the release tension doesn’t seem to help. Is this just an inherent design flaw with SPDS?

are they shimano cleats? You could get round it by having a smoother upstroke, a bit like scraping poo off your shoe, rather than trying to pull your foot out of it…

I get this depending on which shoes I wear. My road shoes (smooth soles) are fine, my MTB shoes with moulded-in tread sometimes pull out.
I guess that the tread interferes slightly with the cleat/pedal locking