I have only hit this on 1 song out of the 4 I worked on today, but flagging in case I hit it with others, or other people see the same issue.
Environment: ST4 Build 1810, iPad iOS 26.0.1
Issue:
On one song, when I go into Song Details -> Regions, instead of seeing the waveform, I see the following:

The spinner just spins forever.
If I change tabs and come back - still spinning.
Close the song, go into another song, come back to the 'affected' song - still spinning.
The song comprises of 3 audio tracks, which are all .WAV (16bit 48kHz) files.
In the ST4 log I see the following:
2025-10-14 18:47:00.217 🔵INFO SongPlayer:267 [b] Loaded song Uptown Funk with 3 tracks and 0 regions into SongPlayer
2025-10-14 18:47:04.409 🔴ERROR MiniPlayerView:164 [b] Error loading waveform: nilError
2025-10-14 18:47:06.640 🔴ERROR MiniPlayerView:164 [b] Error loading waveform: nilError
2025-10-14 18:47:56.103 🔴ERROR ZoomableWaveformView:390 [b] Error loading waveform: nilError
2025-10-14 18:49:21.236 🔴ERROR MiniPlayerView:164 [b] Error loading waveform: nilError
2025-10-14 18:49:22.976 🔴ERROR ZoomableWaveformView:390 [b] Error loading waveform: nilError
2025-10-14 18:49:25.454 🔴ERROR MiniPlayerView:164 [b] Error loading waveform: nilError
Troubleshooting:
I've restarted ST4 - no change
I've rebooted the iPad - no change
The audio plays just fine I don't believe it is corrupted audio files or similar.
I've sent a support email to Peter along with a link to the audio files in this song to download.