No, I don't use Magisk.
Thanks for the information - it may be worth to put a section about Magisk into my "Tips & Tricks" post . . .
That would indeed be kind for those in need. I'll (but only in 10 days) also upload the ramdisk.img files to SF for B540, B550 and B552.(I don't have P9 anymore or any Huawei). When I did have, it was b540 and Magisk v20 4 and the Magisk procedure I commented above perfectly worked.
I can still find on my PC the ramdisk.img from b540 and its patched by Magisk b540 counterpart, and I can share - but only for those who did not upgrade from b540 to b55x (and who are willing to stay on old Magisk)