فَكَأَنَّهُ أَرَادَ بِالْعِلْمِ مَا لَا يَشْمَلُهُمَا
It appears that “knowledge” was intended in a sense that does not include these two.
If “knowledge” is specifically reserved for cognition distinct from probability and reversible conviction, it becomes understandable why solitary reporting and following a jurist are not added as independent entries in the original threefold scheme. This is a restriction of the technical sense of knowledge, not a judgment that those reports or juristic opinions have no value.
Whether a claim should be described as knowledge, probability, or conviction depends on the claim and the strength of its grounds. Without attention to that terminological boundary, the same list of sources can appear inconsistent.