Stock Sales with Code “X” on 1099B

Hello, I have a 1099B that says “Box 5: Non-Covered Securities – Code X (unknown Holding Period)”.  How should I put the data on Form 8949?

1099B has the following:

Box 1a – Number of shares – 80

Box 1b – Date Acquired – “--” (blank?)

Box 1c – Date Sold – 2/22/2023

Box 1d, 6** (what does 6** mean?) – Proceeds - $560

Box 1e – Cost of Other Basis – “--” (blank?)

Box 4 – Federal Tax Withheld – $0

Box 1g – Wash sale loss disallowed - “--” (blank?)

Box 1f – Accrued market discount – blank

Looking at my records, I found the stock issued date was 5/10/2019.  I can’t find the cost on my records, so I searched the internet and found the stock price on 5/10/2019 was $23.

On Form 8949, should I put the information that I found that is not on the 1099B as follows?

Box E “checked” – Long Term transactions on 1099B showing basis wasn’t reported to IRS

column (b) date acquired – 5/10/2019

column (e) cost or other basis - $1,840 (80 shares x $ 23 internet searched price on that day)

column (h) gain/loss – loss of $1,280 ($560 proceed minus $1,840 calculated cost)

Also, what do I put on column (f) and (g)?  Does the Code “X” on the 1099B mean I should put “X” on column (f), or some other code per the Form 8949 instructions?

Or should I put “$0” on column (e) as zero cost, and put the calculated cost of $1,840 based on the internet searched price on 5/10/2019 on column (g) as “adjustment”? If I do this, what do I put on column “f” as code?

Thank you.