Missing icons and data

[AJS]

I have 2 e127 displays running 16 version software.The chart card is Navionics Gold.The helm display which is the slave intermittently boots up missing some navaid icons or tide,current,or marina icons.Sometimes the current icon is present but clicking on it will show a flatline instead of the sinusoidal current diagram.Rebooting the display will often fix this.Sometimes just reclining on the current icon will fix this.
Both displays are.running the same.software version.The chart card is in the master display which does not do this however moving the card to the slave at the helm doesn't seem to solve it.I haven't been doing master.resets after each software upgrade recently.The menu settings are at the appropriate level of detail.
As always thanks for you help.
Alan