Note, this has worked perfectly fine literally up until yesterday, when suddenly for some reason it doesn't work anymore.  For the life of me I can't figure out what's going on.  A powered rail placed on a block had a hopper minecart on it for a furnace array, when going to put items in the hopper minecart the other day, the system didn't work.  Go to investigate, find that the comparator is not detecting items in the hopper minecart either.

I tested the system in creative, worked fine, and tested immediately adjacent to where it is currently build, also worked fine.  Attached are screenshots that include debug screen, demonstrating the unpowered detector rail, placing a minecart on the unpowered rail, and removing the minecart to see the rail remails powered (powered: true).  I also included screenshots of a detector rail on the immediately adjacent block showing an unpowered detector rail, placing a minecart on it to power it, then removing the minecart to return the detector rail to a powered: false state.  

What on earth is going on?  Is this a bug?  The buggy interaction ONLY occurs on four specific blocks where four detector rails have existed for several months, on both 1.14.4, 1.15.1, and 1.15.2, with no issues up until yesterday.  It happens on four specific blocks, all with different coordinates.  Even when the blocks are broken and replaced, the issue persists.  

I have also attached an array of detector rails around one of the impacted blocks, that demonstrate that it is specific blocks where the detector rail stays powered.

The rail is on a chunk border, but I don't think this should matter, since the machine has worked fine up until yesterday?  Any insight at all would be greatly helpful.