Carpet/rug backing has left rubber residue on top of the floor - sealed or unsealed.
(For the same issue on stone top patio furniture (that is a gummy residue from the inside coating of a fabric cover) - see below.
Carpet:
This can happen when a non-skid pad (rubber or latex) is used under a carpet, or it is from the carpet's rubber backing. Note that this is caused by the rubber itself and not from a surfacing finish. Sealed or unsealed, time and temperature can cause the rubber to stick to almost anything including a glazed ceramic tile, slate, unglazed tile. Putting a sealer, or an additional sealer or coating (Aldon Lifeguard) of any kind on top of the flooring will not do any good because the rubber backing will stick to that also. However,
will provide a surface that is easier to patch remove and repair than a sealer.
To clean a surface that has no sealer on it - Test lacquer thinner
To clean a surface that has sealer on it:
- If rubber is stuck to an Aldon water based sealer: Test
- If an Aldon petroleum based sealer: Test Insta-Clean. If that does not work, test lacquer thinner but note that it will remove some sealer also. You might need to repair the area with more sealer.
- If the sealer is not an Aldon sealer - Test Insta-Clean. If that doesn't work, see sealer label to determine what will effect it.
- If Insta-Clean does not remove the residue, you need to move up in aggressiveness and that will probably remove the sealer also. First with lacquer thinner and if that does not work, with our
The sealer will be easy to reapply in that spot. 
To prevent in the future, use a pad underneath that is made of a material that does not cause the problem, but is also not slippery.
Stone Top Patio Tables:
If a patio table (stone or glass) is covered for an extended period of time with a fabric cover that has a rubberized (latex, etc.) coating on the inside, heat / pressure / time can leave a gummy residue on the table top.
Test Insta-Clean as the least aggressive, yet powerful way to break this down and wipe it off. Other more aggressive cleaning materials, such as petroleum solvents might dull the Aldon S-B-S Sealer. If that happens it is not a big problem. Simply spray on more of the sealer.
A better type of cover is the kind with a "fuzzy" fabric interior. These should be easily available.