Low selector failure in anti-surge control system

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Our factory's natural gas compressor 01K001 anti-surge control system consists of three controllers, outlet pressure controller PC01005B, anti-surge controller XC01004, handheld operator HC01004A, a low selector XY01004C and several operation blocks. The outputs of the three controllers PC01005B, XC01004, and HC01004A are used as the three inputs of the low selector XY01004C. After comparison by the low selector, the output with the smaller MV value controls the anti-surge valve. Under normal conditions, the MV value of HC01004A is 101.4%, the output MV value of XC01004 is 100%, and the manual control MV value of PC01005B is around 98%. The low selector gate PC01005B controls the anti-surge valve. When the outputs of the above three controllers remain unchanged, the low selector suddenly switches on the anti-surge controller XC01004, and assigns the output MV value of PC01005B to XC01004. The control mode of XC01004 also changes to MAN (manual) mode, and cannot be set to AUTO (automatic) mode (the surge protection function is lost). However, PC01005B can still control the anti-surge valve at this time. This condition lasted for two days and then got better on its own. This is the first time this has happened to our factory in more than 10 years of operation. Has anyone encountered a similar situation? What is the most likely cause of this situation? Is it caused by interference?