I experience the same problem - deleting the “wrong” data doesnot help as they keep on refreshing. Any solution …otherr then “selling” the BPX and “buying” them under a new asset in GBP - which I find cumbersom.
Yup, YF can have ‘moments’ of been unreliable ! It though features two listings for AVI Global Trust quoted in GBX - ‘LSE delayed’ and ‘Cboe UK’. The data for the latter doesn’t seem to have any issues - Yahoo is part of the Yahoo family of brands.