Found the following validation problem for the NEWS.Rd HTML conversion:
NEWS.html:74:1 (inst/NEWS.Rd:42): Warning: <h4> anchor "Documentation" already defined
NEWS.html:89:1 (inst/NEWS.Rd:54): Warning: <h4> anchor "Documentation" already defined
NEWS.html:104:1 (inst/NEWS.Rd:66): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:116:1 (inst/NEWS.Rd:75): Warning: <h4> anchor "CRAN-Checks" already defined
NEWS.html:130:1 (inst/NEWS.Rd:86): Warning: <h4> anchor "Documentation" already defined
NEWS.html:148:1 (inst/NEWS.Rd:99): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:164:1 (inst/NEWS.Rd:111): Warning: <h4> anchor "CRAN-Checks" already defined
NEWS.html:195:1 (inst/NEWS.Rd:134): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:206:1 (inst/NEWS.Rd:142): Warning: <h4> anchor "Documentation" already defined
NEWS.html:236:1 (inst/NEWS.Rd:164): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:248:1 (inst/NEWS.Rd:173): Warning: <h4> anchor "Enhancements" already defined
NEWS.html:284:1 (inst/NEWS.Rd:199): Warning: <h4> anchor "Changes" already defined
NEWS.html:295:1 (inst/NEWS.Rd:207): Warning: <h4> anchor "Enhancements" already defined
NEWS.html:324:1 (inst/NEWS.Rd:229): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:340:1 (inst/NEWS.Rd:241): Warning: <h4> anchor "Documentation" already defined
NEWS.html:355:1 (inst/NEWS.Rd:253): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:371:1 (inst/NEWS.Rd:266): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:388:1 (inst/NEWS.Rd:279): Warning: <h4> anchor "Documentation" already defined
NEWS.html:409:1 (inst/NEWS.Rd:295): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:430:1 (inst/NEWS.Rd:311): Warning: <h4> anchor "Misc" already defined
NEWS.html:454:1 (inst/NEWS.Rd:330): Warning: <h4> anchor "New-Features" already defined
NEWS.html:478:1 (inst/NEWS.Rd:348): Warning: <h4> anchor "Changes" already defined
NEWS.html:504:1 (inst/NEWS.Rd:368): Warning: <h4> anchor "Enhancements" already defined
NEWS.html:523:1 (inst/NEWS.Rd:382): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:534:1 (inst/NEWS.Rd:390): Warning: <h4> anchor "Misc" already defined
NEWS.html:549:1 (inst/NEWS.Rd:403): Warning: <h4> anchor "New-Features" already defined
NEWS.html:561:1 (inst/NEWS.Rd:412): Warning: <h4> anchor "Bug-Fixes" already defined
NEWS.html:588:1 (inst/NEWS.Rd:431): Warning: <h4> anchor "Documentation" already defined