Newsflash: What is the strategy here?

I’ve viewed around 40 homes in the past 2.5 months, bid on 5, the two properties where my bid was accepted I had to walk after inspection. I viewed a house last week, made an offer of $228,900 on a home with an asking price of $246,000.00 when offers were presenting. With only 3 showings and being active for 7, I was the only bid. The agent accepted my bid but stated he would be waiting 24-hours or something to present to see if there was any more interest. During this 24-hours, the listing changed and a new asking price of $255,000.There was barely any interest in this home. Likely due to neighbourhood. Why would they increase the price if there was only one bid?I accepted the $250K counter, but the inspection was yesterday, and the furnace is from 1988 the watertank 2012, the central air conditioning 1980, the washer is old and jiggles, the windows are old, everything else is in great condition but even at $250 it’s way over comparable sales and my city has the property assessed at just $183K. Do you think I can counter now, after the inspection noting the copper stack, older components, and have them come down or; because of that weird price increase they likely won’t go any lower? What was their tactic with that anyway? Are they not motivated to sell? Thanks.