Brewpi/Uno Rev C shield - Faulty SSRs?

I have two LEC fridges that I’ve wired up and ‘brewpied’ as per your excellent examples/instructions. One of them works perfectly, but the other one is behaving oddly, and I believe it’s to do with the SSRs.
They are effectively latching on, that is they stay on after the signal from brewpi is switched off.
This results in both cooler and heater being on at the same time.
If I disconnect the control signal line to either SSR, that SSR switches off. Reconnecting the control wire to any output, even one that is not configured in the device manager results in the relevant SSR switching on.
I also noticed that the LED connected to the output that I plug into comes on dimly (about half normal brightness.)
I’ve had a professional refrigeration engineer check the wiring, and confirms that all is well in that department.
I’ve connected both brewpis to the other fridge and all works well - everything switches on and off cleanly.
The only components that I haven’t eliminated are the SSRs.

Could these be the problem, and has anyone had any similar problems with these SSRs? They are the ones that the brewpi store recommends and that’s where I bought them.

I meant to say - the SSRs are PQLYT 10A 240Vac 3-38Vdc.

Further to the above posts, I realise that the brewpi/fridge that works contains SSRs that I bought from the Brewpi Store. The other fridge contains SSRs that I bought through ebay, and are slightly different, although both sets are labelled PQLYT. They have similar markings, but no led, and the markings suggest the need for a 470k-560k potentiometer between the 5v inputs, which the working SSRs don’t have. I noticed a similar requirement for the counterfeit Fotek SSRs.

Has anyone any similar experience with these SSRs?