I have never seen that before with the mouse not working in the chest, but in other areas it is.
Having said that, what you are showing in image two isn't the virus chest (see image1 example) as the virus chest remains within the avastUI.
What you have looks more like the Results window, after an avast scan or if you use the Scan Computer, Scan Logs, select a scan that has been completed and select View Results. Now in this window the data is historic, so you cant make and changes/selection as it isn't active and that is why the Apply button at the bottom of the windows is greyed out, inactive.
I have run a test scan with some eicar samples and used the Scan Computer, Scan Logs, select a scan that has been completed and select View Results option I mentioned and the mouse isn't totally inactive, but because this data is historic (not from an active/open scan) then it is correct not to allow any selections. However if you look at image2, you can see my mouse pointer and you can see that where it moves it does track what line it is on.