A short while ago, I reported some discrepancies between the results produced by “lme4” and other R packages as well as Stata. Today I upgraded to the most recent version of “lme4a” and re-ran my model. The error of false convergence disappeared and the new results are very much in line with other packages.
I am glad that the problem eventually got sorted out.
For this version, the adaptive GH quadrature has not been implemented yet; so the only option to estimate a GLMM is laplace transformation.