This mod is great to enable colour concrete without enabling dectorio's painted tiles (which consume an assload of tile slots for stripes variants), but it doesn't use dectorio's crafting group.

Add this to data-updates.lua

-- Dectorio integration
-- If Dectorio crafting tab enabled and Dectorio colour concrete disabled move items to dectorio tab's flooring subgroup
if data.raw["item-group"]["dectorio"] and not data.raw["item-subgroup"]["flooring-painted-refined"] then
for _, color in pairs( colors ) do
local item = color.name.."-refined-concrete"
data.raw["item"][item].subgroup = "flooring-basic"
end
end

Done, thank you for the suggestion and example!

And it's already broken. I 've been looking for some other mod interfering somewhere but failed locating one. I'll try to isolate it and see what comes up.

Ok so you need to have it in data-updates.lua for it to work or it gets overwritten by something. That or dectorio doesn't generate it's item subgroups on the initial loading but it doesn't seem to be that.

Huh, it worked in my testing - would you mind showing the prototype history for those recipes? You can find them with ctrl+shift+e
Imgur

Tile : Base > More Placeable Tiles > Asphalt Paving (Roads) > Alien Biomes > Space Exploration Postprocess
Item : More Placeable Tiles > Space Exploration
Recipe : More Placeable Tiles > bzlead

Note that those are in my version of more placeable tiles with subgroup code moved to data-updates so it works

note that i have checked bzlead and it's not the culprit

I've tested all but Alien Biomes and Space Ex so far, just loading SE now.

Edit: Yep it's space-ex

Pushed an update that applies in data-updates as you suggested. Let me know if this solves your issue, it did in my testing.