Some time ago the “old fashioned” 74xx symbols (with hidden power pins) where replaced with new symbols with a explicit added power-unit. This unit must be manually placed in the schematic and than manually connected to 3V/5V/GND (whatever).
If you attach the project (Kicad-manager–>File–>Archive project) we can look an tell if the autoconnect doesn’t works (bug, unlikely) or if you just used a symbol without hidden power pins.
remark: for attaching a archived project you need to promote yourself to the “basic user” level. Read level for information.