I have spent a LOT of time creating a curtain wall with all the panels and accessories etc. but i find when i make any adjustment to the grid scheme like stretch it, all the doors, windows, frames etc. all disappear leaving me with a basic panel and grid curtain wall. is this a bug, or is it just asking too much of AC to handle?
Try to change your logic how you are building your CW. You have default grid scheme, where you don't have doors, windows etc. It's your default scheme. After you creating custom panels by adding windows and doors. Then, when you make changes to your grid, you actually returning to default grid - and loosing all custom panels. You need to set additional classes for your panels - then you will get more stable grid system.
CW had several major updates (it was introduced in version 13 or 14...). So it gained quite a lot of fixes and flexibility - so we cannot say - it's still not working good.