Challenges in reverse osmosis cleaning

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Dear sea friends: We have recently encountered a serious problem during the RO cleaning process. Before the reverse osmosis cleaning: the inlet pressure was 0.98 MPa, the pressure between stages was 0.78 MPa, the concentration discharge pressure was 0.71 MPa; the pressure difference in stage 1 was 0.2, and that in stage 2 was 0.07. The water production volume was 56 cubic meters, while the concentration discharge volume was 22 cubic meters. The conductivity of the produced water was 4.94. After using alkali cleaning followed by acid cleaning: the inlet pressure became 1 MPa, the pressure between stages was 0.88 MPa, and the concentration discharge pressure was 0.78 MPa; the pressure difference in stage 1 was 0.12, and that in stage 2 was 0.1. The water production volume decreased to 45 cubic meters, the concentration discharge volume to 20 cubic meters, and the conductivity of the produced water rose to 6.59. The pressure differences decreased after cleaning, but the conductivity remained largely unchanged, while the water production volume dropped significantly. We also used only alkali washing for the second set of membranes, and the same issue occurred. Suspecting that it had not been rinsed thoroughly, no cleaning solution was used for the second set of membranes; instead, they were rinsed with a large flow of deionized water (after heating), which resulted in the water production volume dropping by another 15 cubic meters. We use Lanxess membranes from Germany, and such issues have not occurred with either the distributors or the chemical manufacturers. The membrane end caps were removed for inspection, and they were found to be very clean; the distributor has arranged to have the membrane taken to the manufacturer for detailed analysis. I was wondering if any fellow sea traveler knows the reason, or knows of any company where this has occurred. I would be very grateful if you could let me know.