Are G measurements prone to periodic oscillations similar to length of the day oscillations?

A 2015 paper from Anderson et al. suggests that measurements of Newtonian constant of gravitation G are prone to periodic oscillations that are one-to-one correlated with periodic oscillations of measurements of length of the day. Also 2018 measurements by Qing Li et al. (see my previous post) seem to fit this pattern.

Very interestingly the mean result of G value that arises from the analysis (marked green on the picture below) has value of 6.673 899(69) · 10⁻¹¹ m³/(kg·s²), much closer to 6.673 655 21 · 10⁻¹¹ m³/(kg·s²) than CODATA 2014 and 2018 recommended values. For those who didn't read my first post on this blog: 6.673 655 21 · 10⁻¹¹ m³/(kg·s²) is a value that I postulate to link electron rest mass to elementary charge.

2020-07-07 update: See the latest version Elementary Charge, Electron Rest Mass and Newtonian Constant of Gravitation.

comparison of the CODATA set of G measurements with a fitted sine wave (solid curve) and the 5.9 year oscillation in LOD daily measurements (dashed curve)

Anderson, John & Schubert, G. & Trimble, Virginia & Feldman, Michael. (2015). Measurements of Newton's gravitational constant and the length of day. EPL (Europhysics Letters). 110. 10002. 10.1209/0295-5075/110/10002.

Abstract:
About a dozen measurements of Newton's gravitational constant, G , since 1962 have yielded values that differ by far more than their reported random plus systematic errors. We find that these values for G are oscillatory in nature, with a period of P = 5.899 +/- 0.062 yr , an amplitude of (1.619 +/- 0.103) x 10^-14 m³ kg^-1 s^-2, and mean-value crossings in 1994 and 1997. However, we do not suggest that G is actually varying by this much, this quickly, but instead that something in the measurement process varies. Of other recently reported results, to the best of our knowledge, the only measurement with the same period and phase is the Length of Day (LOD - defined as a frequency measurement such that a positive increase in LOD values means slower Earth rotation rates and therefore longer days). The aforementioned period is also about half of a solar activity cycle, but the correlation is far less convincing. The 5.9 year periodic signal in LOD has previously been interpreted as due to fluid core motions and inner-core coupling. We report the G /LOD correlation, whose statistical significance is 0.99764 assuming no difference in phase, without claiming to have any satisfactory explanation for it. Least unlikely, perhaps, are currents in the Earth's fluid core that change both its moment of inertia (affecting LOD) and the circumstances in which the Earth-based experiments measure G . In this case, there might be correlations with terrestrial-magnetic-field measurements.

Full text available at ResearchGate.