PCBNew used to indicate no-connect pads with a fine “X” in the pad. It no longer seems to do this. I have several parts in a design that have both explicit no connect “Xs” on the schematic and a few parts that have no-connect pins in their schematic symbols. I’ve dug around for an option for this feature and cannot find it. KiCAD now assigns a nte name that is in the form “Net-(ref-Padx)” where ref is the reference designator and x is the pad #
Has it gone away, or am I missing it? I’m definitely missing it.
What version Kicad? I don’t remember ever seeing it in pcbnew but I started with version 5. However IIRC highlight net in pcbnew will highlight all NC pads when one is clicked on. Not the same, I know.
I seem to remember that there was a flag that could be selected when importing a netlist (I forget if it is there on the update from schematic) that would allow removing/ignoring single pin nets. Maybe enabling this flag will do what you want?
I also seem to have some vague memories that the diagonal crosses mean that this pin is left unconnected.
First I looked through Pcbnew’s preferences.
I would expect this setting to be in: Pcbnew / Preferences / Preferences / Pcbnew / Display Options /  Show pad indicator
So this indicates there is a indicator setting, but I can not see a difference between a pad with or without a net attached. Then I had a little lightbulb moment. and went back to Eeschema.
In Eeschema there is a setting: Eeschema / Tools / Update Pcb from Schematic / Options / [ ]Delete single-pad nets This setting does work, the single pad nets are deleted on the PCB after update, but I can still see no “No Net” markers on the PCB.
In the PCB I normally show the net names on the pads with: Pcbnew / Preferences / Preferences / Pcbnew / Display Options / Annotations / Net Names / (*) Show on pads and tracks
The combination of deleting the single pad nets and showing the net names on pads does give a clear difference. In the screenshot below, pad 2 has a net attached, the net name is in small lettters on the bottom, and pad 3 does not have a net attached which also makes the pin number text a lot bigger.
It is a different sort of indication, but it seems at least just as usable.
Then there is: Pcbnew / Layer Manager / Items / [ ] No-Connects
I can see no difference on the PCB whether that checkbox is checked or not, but it is the same checkbox as Pcbnew / Preferences / Preferences / Pcbnew / Display Options /  Show pad indicator (If you change one, the other also changes.
It does seem logical that this would turn on/off the blue diagonal crosses in Pcbnew. They are very similar to the no connect flags in Eeschema.
I’m beginning to suspect it may be a bug that this does not show any visible difference on the PCB.
Likewise, the no-net/large pin# approach meets my need. It’s often hard to spot the source or termination of a ratsnest element on a busy board. I think this is actually more usable as it’s more obvious. The X is very light and really only apparent at fairly high zoom levels.
I’m doing my first real design in 5.1.5 after being a long time 4.x user. Liking it a lot overall.
If there is a setting in the menu’s for a “no-connect” marker and it only shows up in the old Toolset (Which I do not have anymore on Linux) then this is a bug.
I spend a bit of time looking at gitlab if this has been reported before, and could not find it.
I do not have the nigltlies installed, so can not check if it’s still in the latest version. If anyone can confirm this, I’m willing to make a bug report for this on gitlab. Also seems a nice opportunity to make these lines a bit wider and a lighter shade of blue. (You can always turn them off if you don’t like them).