unity3d - Sprites are disappearing when I zoom in Unity -

unity3d - Sprites are disappearing when I zoom in Unity -

in scene view when zoom in past point sprites (apart one) disappear , makes near impossible me edit them because become little see clearly.

this started happening fine before , don't think have changed have affected ability show when zoomed in.

the z positions have same of canvas using

unity3d sprite zooming unity3d-2dtools