Thank you for the files.
It seems the source files are 32bit floating format, this cause the issue in uTool, even the 32bit signed format works well.
We can solve this issue with uTool update, until this please re-export those files in different format. You can use the eg the Audacity, open the files then select the export and select 16/24/32 bit signed wav file for output format, then create a new song in the uTool with the new source files.
Thanks for the heads up!