Unable to enable slide numbering in a presentation created from a PowerPoint template

Contexte

  • OS : Ubuntu Noble, session Wayland
  • ONLYOFFICE Desktop Editors installed via snap
  • Presentation file: .pptx, originally created in PowerPoint (custom template)

Hi everyone !

First of all, thanks so much for the amazing work you’re doing with OnlyOffice !

Issue

  • In this specific presentation, the command Insert > Slide Number > Slide Number + Apply to all does not display any numbers on the slides.
  • Even when editing the master slide (View > Slide Master) and attempting to add numbering, nothing appears.

Tests Performed

  1. Created a blank ONLYOFFICE presentation → numbering works correctly (numbers appear as expected).
  2. Applied significant zoom + changed theme → no numbers visible in the problematic presentation.
  3. Verified the master slide:
    • The original PowerPoint master did not contain a number field.
    • Adding a placeholder in the master and reapplying Insert > Slide Number had no effect.
  4. Saved under a new name, converted format (re-saved as .pptx) → no improvement.

Expected Behavior

  • The Insert > Slide Number > Apply to all command should work on presentations imported from a PowerPoint template,
    or

  • At minimum, ONLYOFFICE should be able to add a number field to the existing master after import.

File

  • I can provide an anonymized example file if needed (the problematic PPTX template).