I don't think you have a problem, but we need to go back to basics to explain what I think has happened. Sorry if this gets a bit long-winded but it should add to your "cider education".
Assuming that your hydrometer has a "Potential Alcohol" scale (most simple triple scale hydrometers do), I am guessing that the hydrometer showed the SG (specific gravity) of your starting juice to be a bit less than 1.050 which is typical for apple juice, and after a bit of bobbing around it would read about 6.3% on the potential alcohol scale. This is the alcohol you would get if the cider fully fermented all the way down to SG 1.000, and in fact is probably what you have.
However, hydrometers aren't terribly smart. They don't really measure potential alcohol, they just pretend to. What they measure is the density (or specific gravity) of the apple juice, which we use as a proxy for the amount of fermentable sugar in the juice that can be converted to alcohol and CO2. This might sound a bit imprecise, but it works very well and in any case craft cider makers only want to know the ABV within about 0.5%. A common approach to calculating ABV% is (OG - FG) x 131 where OG is the Original Gravity and FG is the Final Gravity. Different multiplying factors are quoted by different authorities but in practice make a difference of less than 0.2% which is good enough for our needs.
The following are very rough numbers because apple juice composition varies a bit from apple type to apple type.
Just to complicate things, around 80% of apple juice is water and it is the remaining 20% which comprises sugar and assorted non-fermentable stuff like acids, tannins and flavour compounds that affect the density or SG of the juice. Sugar is 80% of that 20%, so within reason, SG can be used as a proxy for the sugar content of the juice and hence potential alcohol. i.e. if you add sugar, you increase the potential alcohol. During fermentation, the sugar converts into roughly 50% alcohol and 50% CO2. Phew! I hope that is clear enough.
So, some sources will show that apple juice with SG 1.050 has 130g/L of "density causing" stuff, others will show that only around110 grams or so of this "stuff" will be sugar that can be fermented into alcohol. The Potential Alcohol scale takes this into account.
I am not familiar with Allulose, but understand that it is about 70% as sweet as sugar, so I am assuming that its effect on juice density would be similar to adding sugar to a fully fermented (SG 1.000) cider. In your case, adding enough Allulose to make a sweet cider could increase the density (or SG) from 1.000 to something like 1.015 (this is typical for a sweet cider and is the equivalent of 40g/L of sugar or a bit over two teaspoons in a 12 oz bottle).
In the above scenario, if you measured the SG after adding the Allulose, the hydrometer would float at 1.015 showing 2% on the potential alcohol scale. This is not the alcohol in the cider but simply the extra alcohol that would be produced if the cider had the equivalent amount of sugar which was fermented from 1.015 to 1.000. But of course, it won't do this because Allulose is non-fermentable and so the hydrometer remains at SG 1.015 (or potential alcohol of 2%), just to confuse you.
Anyhow, that is my guess at what has happened. You still have 6.3% ABV, the 2% doesn't mean anything. Have fun!
