Which size of board are you trying? I just tested the Micro & Standard, both work. I suspect you’re uploading the main zip file which has more then just the Gerbers. Either extract the three JLCPCB production files and upload those accordingly or just download the three production files individually. You start with the Gerber.zip, then later the BOM & CPL.
The main zip, needs extracting on computer first
The three production files, no extra extracting/unzipping needed
To download an individual file, click on the file, you may see text or not depending on the file and if you click on “View raw”. Then click the “download raw file” link.
Micro v4.5 - Gerber_AIO_V4_5_Micro.zip uploaded
Standard v4.5 - Gerber_AiO_v4_5_Std.zip
