@bombay_sapphire have you got this resolved yet? I'm in similar situation and wonder how you handled it in the end. My understanding would be
1. Your liquidation dist. $5150 ($51.5 * 100) recovered the cost basis $3000 ($30 * 100). Treat the difference $2150 as long-term capital gain (assuming you held the stock over 1 year since acquired). Will need to enter $2150 separately in TT as no 1099B for this.
2. Cost basis is reducing to $0 as it's recovered from liquidation.
3. Long-term capital gain from stock sell: $1950 (($19.5 -$0) * 100). This number shall be same as what your 1099B reported.
Note that the total capital gain is still the same $4100, but just different in ways how to report the cost basis and the gains from liquidation dist. Is that aligned what you used in the end?
I also posted similar question here
