Go to the Model View Options Dialog. In the "Stair and Railing Options" panel, check the setting in the "Railing Detail Level in 3D and Section" field. I think it is now set to "Simplified" whereas you should be setting it to "Full" to see the 3D model of Railings properly.
Please note that since this is a Model View Options setting and since Model View Options are saved with Views, whenever you activate a View this setting may change. So you should also check your saved Model View Options Combinations to see each contains the proper setting for this field.
Loving Archicad since 1995 - Find Archicad Tips at x.com/laszlonagy
AMD Ryzen9 5900X CPU, 64 GB RAM 3600 MHz, Nvidia GTX 1060 6GB, 500 GB NVMe SSD
2x28" (2560x1440), Windows 10 PRO ENG, Ac20-Ac27