The scan logs are actually in the Report sub-folder.
It is a shame we have this term scan logs and then avast place them in the report sub-folder.
Why Leaf Fan can't see them is the question.
@ Leaf Fan
The question being, have you enabled the generation of scan logs ?
AvastUI > Scan > Scan for viruses - select the scan > Scan Settings (at the bottom of the window) Report file. Ensure that the Generate report file is enabled, the * for the file name is the default and replicates the scan name for the report file name (image1).