Some users of Google Chrome have experienced problems with the display of StreetView imagery viewed via Classic MapBrowser. StreetView may appear fragmented, displaying whitespace with isolated triangles of imagery.
Users who experienced this problem have reported that it presents after an upgrade of the Chrome browser, usually to versions 49.x or 50.x.
This issue is not specific to Nearmap and has been reported on other sites that use the Google StreetView container, including Google's example page demonstrating embedded StreetView:
Some users have resolved or worked around this problem by:
Using another browser such as Internet Explorer or Firefox
This thread on the Google product support forums suggests that the StreetView display problem is caused by the interaction of certain versions of Chrome with video drivers, and contains some further ideas for troubleshooting.