UC and Salary but not allowed viewings


Just really struggling with understanding this situation and hope to get some answers or solutions.

Some back story…
My partner and I have 3 kids - 7months, 22months and 5yrs. He works full time and has a good salary with bonuses. I lost my job last year and we have a joint UC award (it takes into account his salary and then we get a payment each month)
We rent a 3 bedroom bungalow, have been here almost 2years. The only reason we need to move is due to a major damp/mould issue which the agent/landlord has done nothing about.
We have no rent arrears or utility arrears (never had any in 17 years of renting).
Now I’ve called to arrange viewings for multiple properties, letting agents and enquired on openrent.
Every time I’m refused a viewing or to go onto a waiting list for a viewing because apparently we cannot afford it…
Now I currently pay 100 to 150 more than the properties I’m calling to view.
Why is there such a major issue with accepting UC and a salary- is that not still a total household income?
What can I do to find my family a home? It feels like I’m being punished for losing my job during a pandemic and opting to care for my babies while the world resets and I can work again…
We’re a month away from leaving here and no where to go… just find this so much to take in.

Has anyone gone through this and found a solution?
Can any landlords shed any light on why this is happening? I’m told it’s the landlords not accepting UC, credit agencies, insurance, etc… what is the true reason?