According to the StartIsBack+ 1.7.5 changelog , the specific "deep" improvements in this version included:
: The search bar in the Start menu was expanded to index and find options within the "PC Settings" app, not just traditional programs and files. startisback-plus-1-7-5
: This version improved how the software worked with early builds of Windows 10, which was in testing at the time. According to the StartIsBack+ 1
Are you looking to this specific version for a legacy Windows 8.1 system, or are you troubleshooting a compatibility issue? According to the StartIsBack+ 1.7.5 changelog