Appears that there is missing or incorrect information when attempting to grab the register memory base from an operand within the STOS instruction in X86-64. This was found to exist within version 5.0.1 in the Python pip release version. This appears to have appeared since version v5.0.0 commit 34749cf6b2c9dfc. (That is not release version but just the version I happened to have compiled for easy testing). The expected behavior is below from the v5.0.0 test. The actual results from the v5.0.1 test shows that the instruction base value is now returning 0 instead of 39 for the needed registers.
Work environment
Problem
Appears that there is missing or incorrect information when attempting to grab the register memory base from an operand within the STOS instruction in X86-64. This was found to exist within version 5.0.1 in the Python pip release version. This appears to have appeared since version v5.0.0 commit 34749cf6b2c9dfc. (That is not release version but just the version I happened to have compiled for easy testing). The expected behavior is below from the v5.0.0 test. The actual results from the v5.0.1 test shows that the instruction base value is now returning 0 instead of 39 for the needed registers.
Expected
Actual behavior
Code used for Testing