A phase analysis of a polycrystalline melt crystallisation product was performed using a highthroughput method that combines 3D ED data collection using the commercial software EPU-D from Thermo Fischer Scientific in batch mode with the program edtools for semi-automated data processing and clustering. Over 100 high-quality 3D ED datasets with a consistent rotation range of -40 ° to +40 ° were collected and processed over three days. Benefiting from the accurate unit cell parameter determination, six phases present in varying amounts were identified by hierarchical clustering using the Euclidean distance as the selection criteria. The crystal structure of each phase was obtained, including the two novel crystal structures of GSF-PEG IC-I and GSF-PEG IC-II. The minor phases detected, GSF Forms V and II and GSF-PEG IC-II, were present in too small amounts to be detected by PXRD. The first case of polymorphism within ICs built from the same clinical drug-polymer combination was reported, and the possibility of tuning the stability of an IC \by selecting drugs that form multiple channel solvates was suggested. These results demonstrate the selectivity and sensitivity of the highthroughput method to accurately reveal the phase information of complex crystallisation products, which is significant for drug design where screening for and selecting the optimal crystal form is crucial for the overall efficacy of the drug product.