Hi, in this case delete cache files in wavepad folder:
1. From WavePad, select the Options menu > Audio tab > "Audio working folder" section, check mark the "Use this specified folder" box and copy the folder path.
On our end is > C:\Users\sebastian\AppData\Roaming\NCH Software\WavePad.
2. Paste the path on your windows folder explorer, this will open the Cache contents.
3. Delete all files within this folder.
4. Close WavePad and re open it again.
5. Re load the file and let us know the outcome.