Tier 2 Reverse Factory doesn't recycle intermediates such as copper cables, iron gears, green circuits etc.,

I believe that was changed back in July of 2019, with v6.1.0, for Factorio version 0.17.x
See the top FAQ for this mod here

Tier 2 hasn't recycled intermediates for at least a year now with default settings, that ability has been pushed back to Tier 4 (in order to prevent early-game abuse of the productivity recycling loop). If you want to enable recyclable intermediates at all tiers of recyclers (because either you don't care/plan to abuse the loop, or specifically because you DO want to abuse that same loop), there is a startup mod setting for this.

Oh I think that was the issue, somehow the setting got reset last time I updated the mod, thanks ~

I've checked the mod again and there's no Tier 4 reverse machine even in creative mode

Hm, do you have any big mods that might be changing the tech tree? I've just tested it in vanilla again, and everything appears to still be working. Anything involving Bobs, Angels, Pyandons, Industrial Revolution, etc.

Currently using
AAI Industry
AAI Signal Transmission
Aircraft
Alien Biomes
Alien Biomes High-res Terrain
Armored Biters
Auto Deconstruct
Bob's Assembling Machines
Bob's Enemies mod
Bob's Functions Library mod
Bob's Greenhouse mod
Bob's Logistics mod
Bob's Mining mod
Construction Train
Creative Mod
Dectorio
Disco Science
Even Distribution
Factorio Library
Factorio Standard Library
Fill4Me
Fish Breeding
Flare Stack
Fluid Memory Storage
FNEI
Fully Automated Rail Layer
Healing Ammo
HelicopterRevival
Indestructible Wall
Infinite Fuel
InformaTron
Island Start
Islands World
Jetpack
Memory Storage
Mining Drones
Mouse-over Construction
Nanobots: Early Bots
OSHA - Robot Recaller
Planetorio
Quarry
Recycling Machines
Repair Turret
Reverse Factory
Robot Attrition
RPG System
Schall Tank Platoon
Spidertron Extended
Stone Water Well
Tackle's Autorun
Teleporters
Text Plates
Unlimited Productivity
VehicleSnap
YARM - Resource Monitor

Hm, is there any reason you have both Recycling Machines and Reverse Factory? They do functionally the same thing, reversing recipes into their constituent ingredients? Seems a bit superfluous to have both... but aside from that, this looks like a standard modlist.. just tried testing with Island World/Start, which could have been the most likely culprit, but still working properly.. Planetorio makes no difference... maybe the mismatched combination of bobs and AAI? Nope, tech still appears....

Although with this awkward combination of Islands, Planetorio, AAI, and those specific Bobs Mods, the RF4 technology fails to copy one of the vanilla techs and defaults to red/green (as opposed to the intended red/green/blue/etc), but it still does appear in the list. There's just something... off about your specific modlist, I dunno. Might be best to just give up on it, it's a bit too messy, with too many mods changing fundamentals about the game to trace back the issue. If Recycling Machines is working properly for you, I'd suggest just using that one instead.

(also just noticed, I was wrong about having a setting to enable intermediate recycling for all tiers; the setting I was thinking of just disables intermediate recycling entirely)

I installed the Recycling Machines mod after encountering the issue with Reverse Factory mod, I have also kept enabled mods that I don't use anymore so I'll be trying to disable those and see if does make a difference

Updated: I disabled Planetorio, Construction Train and Schall Tank Platoon and now Tier 4 technology appears o.O

Hm, I will investigate Construction Train and Schall Tank Platoon, even though it doesn't appear that they should affect the tech tree in any major way? There could be some weird interaction between Planetorio and those two though; thanks for narrowing it down!

I can't find any consistent interactions between these mods... depending on what's enabled or not, the tier 4 machine sometimes copies a different tech, and other times it doesn't... it's odd.

I've attempted a fix with v8.0.8, by having tier 4 copy a different technology when bobs assembly is detected without bobs intermediates (which was an actual issue tbh). Maybe this helps re-enable the technology in your game?

The technology is present at the moment in my game, I weren't using those mods I disabled earlier so I don't mind leaving it as it, the only weird thing I noticed is that for some reason Tier 4 requires only Red and Yellow science while Tier 3 requires Red+Yellow+Blue Science, that's odd

Edit:
Never mind I updated the mod and now Tier 4 requires 4 science packs types ~

Yup, that was the main issue that I had noticed and wanted to fix, glad to hear it! Though if you ever do go back to using those mods, I would like to see if I was able to fix that issue as well :D

I have tried to re-enable individually Planetorio, Construction Train and Schall Tank Platoon and in all cases Tier 4 technology still appears, so I guess whatever was causing the problem was fixed in the last mod's update ~

Sweet, great to hear it!