ALMA continuum images of the sample of 67 discs with inner dust cavities (‘transition discs’) for which we do not find a significant proper motion anomaly (|Δμ|/σ_|Δμ|<3) indicative of companions. WISPIT 2 is missing from this mosaic because its ALMA image showing an inner dust cavity (priv. comm.) was not publicly available at the time of publication. The companion separation-mass parameter space in which a companion dominating the astrometric signal can be excluded based on this non-detection is described in Sect. 3.2 (see Figs. 4 and A.3).