Up until E3D Series 3, exporting IFC files was limited by the number of elements that could be processed, because the application was still running in 32‑bit.
We tested to export a Site containing more than 10,000 elements, and the export was not possible due to this limitation.
With E3D Series 4 (Unified Engineering), this issue was resolved, as the application was redesigned in 64‑bit.