Problem with Ecoteck Lisa

I don't know your stove but from what you describe there is a lack of combustion air
dirty stove come to mind when was the last time it had a full cleaning
from burn chamber to top of exhaust . Is the combustion fan working has it
ever been cleaned? Some place to start anyway

Sounds like the stove and/or flue pipe needs a good cleaning. The "Pellets Finished" message happens when the exhaust temperature falls too low, it thinks the flame went because it ran out of pellets.

When was the last time you cleaned the stove, including taking off the side panels to get to the 2 ash clean-out ports accessible from inside the stove?

My cleaning routine (Similar Ecoteck Elena model) :
Every 3 to 5 bags of pellets, I clean my Ecoteck Elena as follows : takes about 10 minutes :
1) Remove Flame trap at top of firebox (triangular metal plate). Be carefull when you remove it so you don't damage the firex. Then vacuum around the heat exchanger tubes and the perimeter of the square opening just below the tubes. A "crevice" tool/nozzle on my ShopVac (with "Cleanstream" HEPA filter) works great. Move the tube scraper to the full out position to vaccum the rear edge of the square opening.
2) Use a soft 2 inch paint brush, gently brush off the Firex, use the vacuum nozzle to gather the dust. DO NOT scrape the Firex with the nozzle : it is fragile ! You won't be able to get all the black soot off the firex...that's OK.
3) Replace the Flame-Trap
4) Vacuum the grate around the burnpot, then remove it.
5) Use a plastic spackle/putty knife and scrape the sides and bottom of the burn pot, then vacuum it, then remove it.
6) Vacuum the inside of burn-pot holder/receptacle.
7) Replace the burn pot
8) Replace the grate.
9) Pull out ashpan and vacuum it
10 Vacuum the bottom of the firebox, where the ashpan sits.
11) Replace the ashpan
12) Clean the glass with a wet (water) paper towel, dry it off with another (dry) paper towel. (NO WINDEX, and clean glass ONLY when it is cool to the touch)
Close it up !

I have never vacuumed my hopper : the Ecoteck auger does not seem to care about fines/dust.

About every ton of pellets, I vacuum out my flue.

At the end of the season (2 to 3 Tons) I take the side panels off, take the exhaust blower off, and open the two clean-out ports and vacuum everything out using a smaller diameter hose/tube, duct-taped into the hose nozzle of my ShopVac, to get into the clean-out ports and into the exhaust blower housing.

You can also use a leaf-blower to clean out the stove, but first disconnect the vacuum line at the exhaust blower outlet duct.