Hi,
It is hard to tell based on only looking at the front-end, but it is most likely a configuration issue somewhere.
– The most common is that the index table is not actually enabled.
– Also, make sure exact matching is disabled
– Common and overlooked problem can be category or other exclusions/inclusions.
These are probably the most common issues related to missing results, but it can be a million other things too. If you want, you can add temporary back-end access and I will check the configuration to see if there is anything.