Exported WAV tracks out of sync when imported into other software

I have had 16 track audio recordings from 1989 with a SMPTE time code converted to WAV and imported into Cubase Pro 12 and then patched the track with SMPTE through my usb audio interface and into my SMPTE Synchroniser which then outputs MIDI to vintage sequencers and drum machines which is working well and I am adding audio tracks to the original recordings.
When I export the tracks in WAV and then test them by importing to Audacity the new audio tracks I have added are now out of sync with the original recordings.
Does anyone know what I am doing wrong and how I can solve this?

I don’t know what you’re doing wrong, but if you can’t figure that out, then you can always measure the delay (which presumably will be identical across all tracks) by adding a bar of clicks (anything with a strong transient), and then use that to correctly align those tracks (in Audacity or Cubase) and export them from there to eliminate any systemic time domain misalignment to the grid.

I have manually realigned a click track in one of tracks which is the only added new track.
I have only imported the audio onto Cubase and the measures are not aligned with the audio so I cannot add measures.