Occasional ContributorCase closed! Many thanks!
Super ContributorAs I said previously, you cannot mix inputs and outputs within the same bus name. You need to separate them out.
And "GPIO_1" is just the name of that jumper in the picture you attached from the DE10-Nano user guide. In other words, you can name the signals whatever you want in your code or schematic design, but they must have different names for input and output signals/busses. Again, you could simply use GPIO_in [15:0] and GPIO_out[19:0]. And then you assign those to the pin numbers shown in the picture to make the correct connections to the GPIO_1 jumper (JP7). Pin AG24, for example, does not need to be connected to a signal named "GPIO_1[16]". The picture is just showing you which physical jumper locations are connected to which I/O pins of the FPGA.
The "auto-assignments" you show in figure 2 do not look like Fitter assignments since I presume that is the All Pins list in the Pin Planner. Fitter assignments do not appear in the All Pins list. They only appear as green pins in the Pin Planner chip view when you select Show Fitter Placements from the View menu or toolbar. User (manual) assignments do appear in the All Pins list and appear as reddish-brown pins in the chip view of the Pin Planner.
Are you using a project template (.par) or something to set the I/O locations and/or pin names for this design? Your issues aren't making sense otherwise.
