Repeating command blocks with /execute if... run fill does not become active

So I was trying to make platform gates for a subway system, and I used a technique that I called "block state entanglement", which uses repeating command blocks to detect the block state of certain blocks and run different commands altering other blocks based on the block. I found out that, even though it runs correctly when executed by a player, does not run when in a repeating command block in always active mode.

The command

execute if block 958 67 -781 minecraft:detector_rail[powered=true]

does not run when on a repeating command block at position (958, 67, -776), but the command

execute if block 958 67 -781 minecraft:detector_rail[powered=false]

runs perfectly fine on a repeating command block at position (960, 67, -776).

The world seed is 8146930324540887234.