Actually I think it's quite normal. Our Syrians have never been that interested in any toys in the cage unless they have food stuck to them
But they still like to know they're there and can get a bit upset if something disappears. If you're taking them in and out for out of cage time that might cause some upset too. I'd leave them there but add something new. They soon get bored and a new chew stick or toy would add some interest.
Their cage is their territory whereas outside the cage they tend to be less territorial and take more interest in things. They really only like hidey places and tunnels anyway
Or food. An example is the cardboard hay house. Our last Syrian Charlie would sit for a good half hour inside it chewing it to bits. But if you put it in the cage he ignored it - because he had other more important things to do in his cage! His routine, his nest, his hoards and his busying about at night.
To add some interest you could make a food parcel out of a toilet roll and put some pumpkin seeds inside (Erin's Hamsters 10 toilet roll toys video shows how). I also like the hyacinth balls - again it will just sit there and be ignored, but if you stick pumpkin seeds under the folds of hyacinth weave they will enjoy trying to get them out!
https://www.amazon.co.uk/Rosewood-Bo...=trio+of+balls
The thing they like most in the cage is lots of substrate, somewhere to sit (on or under a shelf), tunnels to run through (I like the large cork ones as they are an interesting texture, don't sink in the substrate and good for climbing over).