The composite manufacturing process occupies a more prominent place in the aerospace and automotive industries due to the lightweight and high performance of the fibre reinforced polymers. The first step in this manufacturing process consists in forming a flat textile reinforcing structure into a designed (tailored) form. The woven textile preform is widely used in the composite manufacturing for its good draping and flexibility properties. The quality of the final woven composite part depends on the fibre distribution and orientation. It also depends on the absence or presence of forming defects. The reasons of occurrence of defects are related to tool geometry, process parameters, textile characteristics, relative plies orientation, inter-ply friction and fabric-tools interaction. Loss of cohesion in the woven fibre network (intra-ply yarn sliding) is a frequent defect in the forming process and it is expected when the cohesion between the yarns is weak or when the blank holder pressure is high. However, the mechanism of formation of this defect is not fully understood. In the present study, forming experiments with friction-based holder have been conducted for one layer 2x2 twill woven carbon fabric (HexForce 48600 C 1300) in three fabric orientations and also for two plies of this fabric with different relative plies orientation. The occurrence of the intra-ply yarns sliding has been observed in the different configurations and as a function of the blank holder pressure. A correlation between the occurrence of this defect and the fabric orientation has been observed. Otherwise, the effect of the fabric orientation, number of plies, relative plies orientation and blank holder pressure on the recorded forming force and on the fabric in-plane shear is also reported and analysed. That permits to better understand the multilayer woven fabric behaviour during forming and this leads to a better understanding of the loss of cohesion defect within the woven fibre network (intra-ply yarn sliding). The mechanisms associated to the appearance of this defect and their dependency on the process parameters and the textile preform characteristics will be discussed and presented in this work.